Study on biological characteristics and seed production techniques of snakehead (channa lucius cuvier 1831)

MINISTRY OF EDUCATION AND TRAINING
CAN THO UNIVERSITY

ABSTRACT OF DOCTORAL DISSERTATION

AQUACULTURE AND FISHERIES
CODE: 62 62. 03. 01

TIEN HAI LY

STUDY OF BIOLOGICAL CHARACTERISTICS
AND SEED PRODUCTION TECHNIQUES OF
CHANNA LUCIUS CUVIER 1831

SCIENTIFIC SUPERVISORS:
1.Dr. BUI MINH TAM
2.Assoc. Prof. Dr. TRAN THI THANH HIEN

Can Tho, 2016


The work was completed at the College of Aquaculture and Fisheries, Can Tho
University

Scientific supervisors:
Supervisor 1: Dr. Bui Minh Tam
Supervisor 2: Assoc.Prof. Dr. Tran Thi Thanh Hien

The dissertation was defended before the committee marking the university-level
dissertation
Meeting at…………………………………………………………………

Time……………………………Date……………………………………..

Reader 1: ……………………………………………………………
Reader 2:……………………………………………………………
Reader 3:……………………………………………………………

The dissertation available at:
1. The LRC, CTU
2. The National Library
1


GENERAL DESCRIPTION OF THE DISSERTATION
1.1. Introduction
Channa lucius Cuvier 1831 which belongs to snakehead is found in freshwaters like rivers,
lakes, canals, rice fields and forests of nature conservation in the Mekong River Delta (MRD).
Channa lucius meat that is tasty and appetizing people has respiratory organs with natural air, so it
is easy to feed and the fish can live well in water from 5.5 to 6.0 low pH (Rainboth, 1996; Lee and
Ng, 1994). Many people feeding fish in the MRD think that the fish has very promising
development of commercial products, especially cultured in ponds, pens and cages. Currently, the
main sources of Channa lucius fries are exploited naturally in small quantities and with
insustainable quality. Meanwhile, the studies of this species is not much and the information is
only limited in the initial basic research on biological characteristics and natural reproductive
techniques. Therefore, the study of growing Channa lucius into a new cultured species which will
have a great effect in the diversification of cultured species, thus contributing to reducing risks in
farming and food supply needs for society, is a matter of urgency. As a result, the topic "Study of
biological characteristics and seed production techniques of channa lucius Cuvier 1831" is
performed.
1.2. Goal
It is to provide scientific arguments about the biological characteristics, and reproductive

and rearing techniques of Channa lucius. The success of the project will contribute greatly to the
development process of Channa lucius hatchery to supply artificial fish for aquaculture systems
and renewable fish resources in the wild in the Mekong Delta as well as in the whole country.
1.3 Research content
- Research on the biological characteristics of Channa lucius.
- Research on feeding Channa lucius to grow out in the pond.
- Research on stimulating Channa lucius to reproduce artificially.
- Research on the development characteristics of the digestive tract and the optional index of
feed of fry.
- Research on timing to substitute fresh food by processing food (PF) in the fry stage.
- Assessing the possibility of using efficient industrial pellets in the phase rearing fish fry to
breeding.
1.4 The scientific and practical significance of the dissertation
The dissertation is a systematic and comprehensive research on Channa lucius. The results
of the dissertation is the important scientific database and good reference source for teaching and
further studies. The results of this study will contribute to enriching the basic research on
biological characteristics, traits of developed gastrointestinal tract and the food choices of Channa
lucius in Vietnam.
The results of the growout techniques for brood, stimulating fish reproduction and
techniques rearing Channa lucius from fry stage to fingerling are the original science-based
support for the practical local apps in highly effective productivity.
1.5 The breakthrough of the dissertation
The thesis is the first comprehensive study on the biological characteristics of Channa lucius
as follows: identifying ecological features, growth characteristics, nutrition and reproductive
biology.
Channa lucius are mature in the pond by growout with cheap fish (75.0%) and industrial
pellets (72.7%). It is able to identify the measures to stimulate effective reproductive Channa
lucius from a combination of physiological and ecological factors. At 2,000 UI HCG. kg-1 male
and 500UI HCG 2 mg combination with cerebral lobes. kg-1 females at pH 5.5 to 6.0, 28-29oC
2

temperature, dissolved oxygen 5-6 mg/l and the substrate for fish nesting slender vegetables, after
injecting females 37-40 hours, the percentage of spawning with farrowing rate is 83.3%, the
recovery rate is 95.3% and hatchability is 82.6%
The development of the digestive tubeof Channa lucius is complete when the fish is 20 days
old; the thesis has identified food choice index from fry stage to 30 days old; it is determined that
the time of the 16th day is suitable for the replacement of live food by processing food (20%
degree of substitution of FP/day) to ensure high fish survival rate and good growth.
In particular, the thesis has been successful in using industrial pellets to run Channa lucius
from fry to breed. These results contribute to solving the problems of fresh food in the nursery,
help reduce costs, improve production efficiency and expand scale of commercial fish farming in
the Mekong Delta.
The success of the thesis is a huge motivation and a basis to accelerate breeding career of
initiative development of Channa lucius, fish supply seeds for regeneration of Channa lucius
natural resources and aquaculture in order to create a lot of fresh fish products to meet the needs
of society.
* The layout of the thesis
The thesis consists of 139 pages (excluding appendices) which include the following
sections: Chapter 1: Introduction of 4 pages; Chapter 2: Overview of 26 pages; Chapter 3:
Materials and Research Methods of 25 pages; Chapter 4: Results and discussions of 68 pages;
Chapter 5: Conclusions and recommendations of 2 pages; (5) References of 14 pages; The thesis
has 36 tables and 51 figures.
RESEARCH METHODS
3.1 Time, place and subject of research
The study was conducted in 2010-2014. The study of biological characteristics was done
with 968 samples in U Minh District-Ca Mau Province and Long My District-Hau Giang Province.
The studies were conducted in freshwater fish farms, the CAF Laboratory, the College of
Agriculture and Applied Biology, Can Tho University. The research is on Channa lucius (Channa
lucius Cuvier, 1831).

3.2 Research Methods
3.2.1 Research chart: The research on biological characteristics was conducted first, then
the next research contents were conducted as subsequent growout, spawning and fish hatchery.
3.2.2 Research Methods of biological characteristics
3.2.2.1 Methods of analysing morphological characteristics
Body shape, head shape, location and size of the mouth of Channa lucius specimens were
studied by the method of Pravdin (1973); Rainboth (1996). The quotas counted as scales and fin
rays followed Holden and Raitt (1974). The morphological indicators were measured according to
Lowe-McConnell (1971), Grant and Spain (1977) (quoting Pham Thanh Liem and Tran Dac Dinh,
2004). The research on digestive systems of fish focused on organs like the mouth, teeth, comb
gills, esophagus, stomach, intestine, cecum (Lagler et al., 1977) and Bond (1996).
3.2.2.2 Methods of analysing the growth characteristics
The correlation equation between length and weight is determined by the formula of the
King (2007)
W = aLb
Where: W: whole body volume (g); L: fish body length (cm); a: constant of conditions; b:
growth Coefficient.
3.2.2.3 Methods of analysing nutritional attributes
3


a. Relative Lengh of the Gut RLG (RLG - Relative Lengh of the Gut)
The Relative Lengh of the Gut between intestinal length and body length is calculated
according to the formula of Al-Hussainy (1949).
RLG = Li/ L
Where: Li: length of the fish intestine; L: length of the fish body.
b. Determination of Channa lucius nutrition spectre.
Nutrition spectre of mature Channa lucius is determined by the volume method of Biswas
(1993). Determination of the dry weight and of each food sample by analytical method AOAC
(2000)

3.2.2.4 Methods of analysing reproductive biological characteristics
* Determining the condition factor (Condition factor-CF)
Determination of condition factor by sex and formula-based King (2007).
CF = W/Lb
Where: W: Weight of fish body (g); L: fish body length (cm). b: the growth factor is
determined from the equation W = aLb (a is condition factor).
* Gonado Somatic Index (GSI)
Gonado Somatic Index is defined by gender and by the formula of Biswas (1993).
GSI (%) = 100 * Wg/ W
Where: Wg: gonads weight (g);W: Body Weight (g).
Determining the stage of gonad development is based on hierarchy of sexual mature of fish
by Nikolsky (1963).
Templates of histological staining gonads is done with haematoxylin and eosin according to
standard histological methods of Drury and Wallinton (1967) and Kiernan (1990)
* Fecundity
Fecundity is determined on the amount of female fish eggs with the gonads in stage IV and
oocyte number of Banegal formula (1967).
- Absolute fecundity (Absolute fecundity-Fa )
Fa (egg/ female) = (n * Wg )/ Wm
Where: Wg: ovary weight (g);Wm : Sample egg weight retrieved to count (g); n: Sample egg
number retrieved to count.
- Relative fecundity (Relative fecundity-Fr )
Fr (egg/kg of female) = Fa /W
Where: Fr: Relative fecundity; Fa: Absolute fecundity;W: Weight of fish body (g).
* The average length of first maturity
The average length of first maturity (Lm) calculated by the formula King (2007).
P=1/(1+e -r*(Ltb-Lm))
Where: P: Percentage of maturity (mature fish when gonad reached stage III according to
maturity ladder Nikolsky (1963); r: correlation coefficient; Ltb: The medium length of fish body;
Lm: The average length of first maturity.

3.2.3 Hatchery Method
3.2.3.1 Survey on aquatic environment where Channa lucius reproduce naturally
The work conducted a survey on environmental factors on Long My II channel (KC.II), 2
channels of grade III (KC.III) and three interior canals (K.ND) in regions of 2 communes Luong
Tam and Luong Nghia, Long My district, Hau Giang province. The environmental survey period
4


lasted from January to June, 2011, monthly water was measured twice: in phase 1 it was measured
on days 14, 15, 16 (al) and in phase 2 it was measured on days 24, 25, 26 (al), each channel
surveyed 2 points (the beginning and the end of the sources) and at each measurement point 3
indicators are pH, temperature, dissolved oxygen. Determination of pH and temperature indicators
was measured by the ECO pH (HI 9813-5) and Oxygen indicators were measured by HANNA (HI
9142).
3.2.3.2 Research methods of broodstock growout
*Testing Systems
Broodstock Channa lucius growout experiments were conducted for 4 months (12/2011 to
3/2012). The experiment was arranged in a grid system (2x4x1,5 m) with a mesh size of 0.5 cm
and put in the earth pond with an area of 500 m2, 1.2-1.5 m deep, the water in the pond is
exchanged regularly according to tide and a minimum water level of 1 m was maintained
* Experiment Fish: Healthy fish with uniform size of about 90-115 g / head.
* Dietary treatments: Trash feed was ground and mixed with 1% wool to increase adhesion
and industrial pellets are moistened with water before feeding. Feed was put on the floor and
placed in the grids in feeding period.
* Arranging experiment
The experiment was completely random, including two treatments (trea). Each treatment
was repeated 3 times, and each iteration has 30 pairs of Breeders: Treatment 1 (trea 1) used 100 %
trash fish feed; Treatment 2 (trea 2) used 100% industrial feeding pellets.
* Feeding
Positive growout period was in 2 months and feeding in all treatments was as follows:

6%/day (pellets); 10%/day (trash); growout period maturing in 2 months left feeding 3%/day
(pellets), 5%/day (trash fish meat).
* Analysing indicators
Before the experiment layout, we randomly collected 20 fish breeders in the fish's
anatomical experiments to determine the initial biological indicators. During growout periodically
on the last day of each month we collected 20 broodstock (randomly by gender) in each treatment
to analyze some indicators of reproductive biology (maturation rate, GSI, CF, fecundity) and
measured environmental factors (pH, temperature, dissolved oxygen).
3.2.3.3 Methods of spawning
a) The experiment probe
We chose healthy broodstock, with ripe gonads and 90-450g weight. The fish were injected
with reproductive stimulants right of chest fin position. Then, the fish were put in the grids (0,5m3)
in an area of 2m3 cement tanks, each tank had 2 grids.
Experiment 1: Stimulating Channa lucius to reproduce with HCG
Table 3.3: Dosage of HCG injections for broodstock.
Treatment
HCG injection on females (UI)/kg
HCG injection on males (UI )/kg

1
2
3

Females (number)

Dosage

Males (number)

Dosage

3
3
3

500
1,000
1,500

3
3
3

1,000
2,000
3,000

5


The experiment consists of 3 treatments with completely random layout, and each treatment
has 3 pairs of broodstock. Females and males are injected at the same time and with the same
HCG dosage presented in Table 3.3.
Experiment 2: Stimulating Channa lucius to reproduce by LH-RHa + DOM
The experiment consists of 3 treatments with completely random layout, and each treatment
has 3 pairs of broodstock. In the laboratory experiments, the male fish are injected with LH-RHa
+ DOM before the females, in the control treatment the males and and females are injected with
only physiological saline water(0.9%). The injectable time and dosage with LH-RHa + DOM is
presented in Table 3.4.
Table 3.4: The injectable time and dosage with LH-RHa+DOM for broodstock.

Treatment
Injection with LH-Rha on the males
Injection with LH-Rha+DOM on the
(µg)/ kg
females (µg+mg)/ kg
number
Start
24h
48h Number (unit) Start
24h
48h
(unit)
Controlled
3
0
0
0
3
0
0
0
1
3
0
80
120
3
0
0
100+4

2
3
80
120
150
3
0
0
100+4
Experiment 3: Stimulating channa lucius to reproduce with HCG + pituirary extracts
(PE)
The experiment consists of 4 treatments with completely random layout, and each treatment
has 3 pairs of broodstock, the males are injected before females are; the controlled group has
injections as similar as in experiment 2. The time and dose of injections of HCG + PE are shown
in Table 3.5.
Table 3.5: The injectable time and dosage with HCG + PE for broodstock
Treatment
Injection with HCG on the males
Injection with HCG + PE on the
(UI/ kg cá)
females (UI+mg)/kg
number
Start
24h
48h
number
start
24h
48h
(unit)

(unit)
Controlled
3
0
0
0
3
0
0
0
1
3
0
2,000
0
3
0
0
500+1
2
3
1,000
2,000
0
3
0
0
500+1
3
3

1,000
1,000
2,000
3
0
0
500+1
Experiment 4: Stimulating Channa lucius to reproduce with HCG + PE and reducing
water pH (5.5 to 6.0)
Table 3.6: The injectable time and dosage of HCG and PE on the broodstock in combination with
reducing water pH (5.5 to 6.0).
Treatment
Injection with HCG on the males
Injection with HCG + PE on the
(UI/ kg fish)
females (UI+mg)/kg
number
start
24h
48h
number
start
24h
48h
(unit)
(unit)
Controlled
3
0
0

0
3
0
0
0
1
3
0
2,000
0
3
0
0
500+2
2
3
1,000
2,000
0
3
0
0
500+2
3
3
1,000
1,000
2,000
3
0

0
500+2
The experiment consists of 4 treatments with completely random layout, and each treatment
has 3 pairs of broodstock. HCG Injections on the males and HCG + PE on the females. The males
6


are injected before the females are. In the controlled treatment both the males and females only
receives 0.9% physiological saline water. The time, dosage and interval between 2 injections of
hormone are shown in Table 3.6.
b. Main experiment: stimulating Channa lucius to reproduce
This experiment was designed based on the results of the exploratory study on stimulating
fish spawning in the experiments 1, 2, 3, 4 and selecting the best exploration results such as
selecting concentrations of HCG + PE and methods of injection in treatments 1 and 2 of
experiments 4 to arrange this experiment. The experiment was conducted with completely random
layout consisting of 3 treatments, and each treatment had 12 pairs of brood stock and each pair
was located in the same grids set in a cement tank of 2 m3. The time, dosage and the gap between
the male and female injections are presented in Table 3.7
Table 3.7: The injectable time and dosage with HCG and PE lobe and the injection for broodstock
are combined with reducing water pH (5.5 to 6.0) in the main experiments.
Treatment number
Rate
HCG on the males
HCG + PE on the females
(unit) male/female
(UI/kg)
(UI+mg)/kg
start
24h
materia start

48h
materi
l
al
ĐC
24
1/1
0
0
0
0
0
0
1
24
1/1
0
2,000
2,000
0
500+2 500+2
2
24
1/1
1,000
2,000
3,000
0
500+2 500+2
Note: In the controlled treatment both the male and female are injected with only physiological

saline water 0,9%.
The water used in the experiment was over filtered and adjusted pH dropping from 7.0-8.0
to 5.5-6.0 with phosphoric acid (H3PO4), 28-29 oC temperature, dissolved oxygen 5-6 mg/l and
the substrate for fish nesting with slender vegetables.
c. The criteria for assessing reproductive outcomes
Effective time (hours), spawning rate (%), fertility rate (%), hatching rate (%)
3.2.4 Methods of development characteristics of gastrointestinal tract and selecting
indicators of fish feed for fry Channa lucius
* Testing Systems: The fish, after eating the yolk, was transferred to spawning in small
ponds with the size 2x3x0,5m, the pond bottom with 25 cm thick layer of mud, the stocking
density of 2/liter; the water in the pond is aired slightly to ensure dissolved oxygen for fish to
grow.
* Sources of food: Before stocking fish in the pond, the water is breeding natural food by
mixing concentrated feed (42.2% protein) with water at a dose of 10 g/m3 and successive
fertilizers for 2 days. During the nursery, we hang fabric bags containing fish fry 5 g/m3 to
maintain the natural food in the duration of the experiment.
* Collecting and analyzing morphological samples of digestive tract
- Collecting samples: Fish samples are collected in the old days 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15,
20, 25, 30 and 10 specimens are collected each day to observe life and photograph the
development stage of gastrointestinal tract, intestinal length measurement, body length, yolk size
and the open mouth of the fish.
- Method of analysis: Individuals from the age of 1-15 days are observed shapes of the
digestive tube on a microscope with eyepiece micrometer to capture and measure the length.
When the fish are 16-30 days old, the digestive tube indicators are measured by the naked eye on
a ruler with an accuracy of 1 mm.
* Method of determining the width of the fry mouth
7


Shirota (1970) describe fish mouth widths by the following formula

MH (90o) = AB x 2
Where: - AB is the length of the upper jaw; MH is the width of the mouth (mm)
* Method of determining RLG
RLG is the ratio between the length of the intestines on the body length which is calculated
according to the formula of Al - Hussainy (1949).
* Method of histological analysis of gastrointestinal tract
Fish samples are collected in the old days 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30 and 30
specimens are collected each day to observe life. The tissue template of the fish digestive tract is
coloured with hematoxylin-eosin (H & E) by histological method described by Drury &
Wallington (1967) and Kiernan (1990). We conduct the specimen observation of the
gastrointestinal tract tissue on a microscope (4X, 10X, 40X) to photograph to identify the
structural variation of the digestive organs such as oral cavity, esophagus, stomach, intestines.
* Determination of food choice index (E)
- Sampling: Samples of plants, aquatic animals and fish are collected on days 2, 3, 4, 5, 6, 8,
10, 15, 20, 25, 30 after the layout. Every day 20 units / samples are received preserved in
commercial formalin solution 10%.
- Analysis of water samples:
The qualitative analysis of phytoplankton species and animals is under the document
classification of Shirota (1966), Dang Ngoc Thanh et al (1980), Boltovskoy (1999).
The quantitative analysis follows method of Boyd and Tucker (1992).
- Analysis of food in the digestive tract of fish: the nutrition spectro of Channa lucius fry is
determined by the number method of Biswas (1993).
- The electivity fish food index (E): Ivlev (1961) expressed food electivity index E
(electivity Index) by formula

ri – pi
E =
(ri + pi)
Where: ri: is the percentage of food found in the gut out of foods in the intestines of fish; pi:
means the percentage corresponding foods found in the environment in general foods in the

environment.
3.2.5 Method of channa lucius neursing
3.2.5.1 Determining the time of processed food (PF) of channa lucius in stage 4-30 days
old
* The laboratory system: an experimental system consists of 12 plastic tanks with a
volume of 60 liters per tank. The experiment was completely random layout with 4 treatments
(Trea) converting various PF including: (Trea 1) converter of PF from the 16th day after the run;
(Trea 2) converter of PF from the 13th day after the run; (Trea 3) converter of PF from the 10th
day after the run and (Trea 4) converter of PF from day 7 after the run. Each treatment was
repeated 3 times.
* Experiment Fish: Fish used to arrange experiments are from artificial breeding source
and we selected 4-day-old larvae which had spent yolk and fish with an average initial length of
0.87±0.01 cm (0.002g/unit). We randomly assigned 100 fish in each plastic tank containing 50
liters (density of 2 fish/liter) and run for 30 days.
* Experiment Food: Live foods used in the experiment is moina, earthworms; Processed
8


food (PF) were processed between concentrated food (42.2% protein, 3.20% fat, 5.40% ash,
24.8% NFE) mixed with minced trash fish meat (81,65% protein, 2.68% fat, 5.47% ash) with the
blending ratio of 1/1.
- During the experimental feeding on demand, every day feeding 2 times at 7 and 16 o’clock
in the foods moina, earthworms and PF. The food intake from day 1-3 was added with moina at 24 larvae/ml/day; 4-15 day with cut-chunk worms around 2-4g/tank/day; PF amount from 7-15 days
is around 2-4g/tank/day and PF amount from days 16-30 with 4-6 g/tank/day.
- Until the replacing day, treatments have not replaced PF and the fish are fed with worms.
By the time of days 7, 10, 13, 16 after the run, the worms are replaced gradually by PF presented
in Table 3.9
Table 3.9: Methods of PF gradually replacing in all treatments
Day
Methods of replacing PF

1
80% worms + 20% PF
2
60% worms + 40% PF
3
40% worms + 60% PF
4
20% worms + 80% PF
5
0% worms +100% PF
3.2.5.2 30-60 day old Channa lucius Nursery with industrial pellets with different
stocking density on the tank
* Testing Systems: Experiments run from fry to fingerling on plastic tank of 60 liters (50
liters), run time is 30 days. The experiment had 4 treatments run in the stocking density of 1
head/liter; 1.5 units/liter, 2 fish/liter and 2.5 fish/liter and were arranged completely randomly and
each treatment was repeated 3 times.
* Experiment Fish: Fish derived from semi-artificial reproduction and used concentrate
feed well. Originally, fish size is 2.40 to 2.46 cm/head (wieght from 0.135 to 0.153 g/head) and
the difference in the length and weight of fish initially in the treatments are not significant (P>
0.05).
* Treatment Dietary: Concentrate dietary with 42.2% protein, 3.20% fat, 5.40% ash,
24.8% NFE. The amount of feed used in the experiments is 7-10% body weight and feeding 2
times a day at 7 o’clock and 16 o’clock.
3.2.5.3 The track indicators
- Environmental indicators: temperature, oxygen and pH are measured 2 times a day at 7
o’clock and 14 o’clock. Temperature (°C) and pH are measured by the ECO pH; dissolved oxygen
is measured by HANNA 98172. Nitrite index is determined by Griess llosvay method,
colorimetric spectrophotometer is at 540 nm wavelength and it is measured 1 time/1 week at 7 pm.
- Ending the experiment, we caught 30 fish in the tank randomly to determine volume,
measure the length, calculate the growth rate according to DWG day (g/day), specific growth rate

- SGR (%/day), coefficient of variation in the volume of fish (CV) and compute survival rate
(Survival Rate-SR),
3.3 Data processing
Data was analyzed with average value (Mean), standard deviation (Standard deviation) using
Excel version 6.0 program. We analyse Factor ANOVA compare compare the difference between
the means of the treatments by DUNCAN test in SPSS 16.0 software.

9


RESULTS AND DISCUSSIONS
4.1 Morphological characteristics Channa lucius
Survey results of morphological criteria of Channa lucius (from 16.3 to 40.5 cm in length,
weight 47-637 g/fish) are presented in Table 4.1.
Table 4.1: Morphological criteria of Channa lucius (n= 186 samples).
Minimum Maximum

Mean

D (number of back fin rays)
A (number of anus fin rays)
P (number of chest fin rays)
V (number of back belly rays)
Number of gills in the first arc

38.0
26.0
16.0
6.00
19.0

41.0
29.0
18.0
6.00
22.0

39.8
27.4
16.9
6.00
20.7

Standard
deviation
0.85
0.79
0.70
0.00
1.07

Biometric index
Standard length/body height
Standard length/head length
head length/eye diameter
eye diameter/Standard length
Head length/distance between eyes
distance between eyes/Standard length

4.28

2.48
5.78
0.03
1.87
0.04

7.78
3.53
10.3
0.06
8.73
0.18

5.63
3.02
7.86
0.04
4.70
0.08

0.48
0.11
0.78
0.004
1.18
0.02

Criteria

Through observation of Channa lucius digestive organs it is shown that Channa lucius has

upper-shaped mouth and its mouth stretches and touches the vertical line drawn from the back line
of the eye and it can be flexible. The teeth are pointed, strong and sharp. Lower teeth and palate
teeth are dog-like ones. Gill rakers bones arranged in two rows on the gill arc and they turn into
many sharp thorns. The esophagus of the Channa lucius connects mouth to the stomach cavity. It
is a short but straight line developing horizontally, with thick walls and muscles in many folds
similar to the esophagus of seabass, Scomberidae, and Channidae (McMillan, 2007; Lagler et al.,
1977). The stomach of Channa lucius has bag-shaped, short, large size and thick wall, with many
inside folds. Its stomach is U-shaped like the one of some fish species, such as snakehead fish
(Nguyen Anh Tuan et al., 2004), ca leo (Phan Phuong Loan, 2006). Adult Channa lucius has 2
tubular cecum with a sealing head and the other end attached to the digestive tube junction
between the stomach and intestine, cecum number of fish like the one of Channa striata (Channa
striata) (Lagler et al., 1977, Ramel, 2009). The fish gut is straight and short. Its walls are thick
and the gut length (Li) is generally shorter that the body length (L) and similar to the gut of other
carnivorous fish species (Nikolsky, 1963).
4.2 Environment where Channa lucius with natural distribution
Survey result indicators of temperature, pH and dissolved oxygen (DO) of the canal level II
(CL.II), canal level III (CL.III) and on-farm canals (OFC) in the localities Luong Nghia and
Luong Tam communes, Long My District, Hau Giang province are presented in Table 4.2.
Environment for Channa lucius breeding is the basins of CL.II, CL.III with flowing water and less
water exchange OFC. Results showed that dissolved oxygen ranges from 3.43 to 5.53 mg/l,
temperature ranges 28,5-30,3oC. In particular, factors such as pH environment where Channa
lucius are distributed in relatively low breeding season (5.4 to 5.67). However, the above
environmental factors range in adapted areas for individual development of Channa lucius (Boyd,
1990).
10


Table 4.2: The factors of environment where Channa lucius are distributed naturally
Area
Sample

pH
Dissolved oxygen
Temperature (oC)
location
(mg/l)
Beginning
Ending Beginning
Ending
Beginning
Ending
source
source
source
source
source
source
Luong
CL.II
5.60±0.17 5.57±0.15 5.53±0.25
4.63±0.68 29.5±0.50 28.5±0.76
Nghia
CL.III
5.43±0.21 5.43±0.06 5.37±0.21
4.83±0.49 29.3±0.29 29.5±0.50
commune OFC
5.47±0.14 5.40±0.10 5.40±0.20
3.97±0.47 30.3±0.29 29.3±0.29
Luong
CL.II
5.67±0.31 5.60±0.26 5.48±0.40

3.56±0.44 29.6±0.58 29.5±0.50
Tam
CL.III
5.53±0.25 5.55±0.17 5.47±0.23
3.45±0.40 29.8±0.76 29.6±0.29
commune OFC
5.50±0.10 5.40±0.20 5.33±0.06
3.43±0.21 30.3±0.29 29.8±0.76
Note: CL.II (Canal level II); CL.III (Canal level III);OFC:On-farm canal.
4.3 Characteristics of Channa lucius growth

Khối lượng (g)

800
700
600

3.18435
3,0513
W =W
0.0053L
= 0,008L
2
n = 968
R = 0,9979

500

n = 968
R2 = 0.9591

400
300
200
100
0
0

5

10

15

20

25

30

35

40

45

Chiều dài (cm)

Hình 4.5: Tương quan chiều dài và khối lượng cá

Regression correlation between fish length and weight is very close by the equation W=

0.0053L3,18435, with a correlation coefficient R2 = 0.9591 (Figure 4.5); Regression correlation
between the length and weight of fish is very close by the equation W=0.0044L3.2494 with index
R2=0.9157 (s=401, L from 16.3-36.0 cm, W from 49.0-550 g/fish ), the survey results on male
sample (s) also showed that regression relationship between the length and the body weight by
equation W=0.0047L3.2178 with index R2 = 0.9434 index (s = 494, L from 14.6 to 38.2 cm, W from
46.0 to 639 g /fish). The survey results shown in Figure 4.5 shows the growth in the size and
weight of the fish is not uniform under the development stage of the fish body. In early life, the
fish grow faster in length than the increase in volume, and when the individual phase achieves a
certain size and transitions to sexual maturity, the growth in length slowdowns and the volume
growth is fast.
4.4 Characteristics of Channa lucius nutrition
4.4.1 Characteristics of mature Channa lucius feeding
The results determined the rate of the gut length on the body length (RLG) of Channa lucius
are shown in Table 4.3.
Table 4.3 shows RLG <1. It is base on the value of RLG to show Channa lucius belong to
violent fish group using the animals as food. According to Biswas (1993), the species of fish
which are going to eat animals have a ratio of gut length/body length ≤ 1.
11


Table 4.3: The length of the intestine, the body length and RLG of Channa lucius (s = 874).
Mesearements
Mean±STD
Minimum
Maximum
Total length (mm)

214±65.3

7.53

405

Gut length (mm)

130±45.7

3.70

270

Rate RLG

0.61±0.1

0.25

0.95

4.4.2 Nutritional spectrum of wild Channa lucius
The survey results of nutritional spectrum of wild Channa lucius (L of 16.3 to 40.5 cm, W of
49-680 g) by the volume method (Biswas 1993) shown in Figure 4.8 consist of 4 types of food
and all kinds of percentages are as follows: Lowest detritus (6.3%), followed by mollusks (7.3%),
worms (14.7%), crustaceans (14.8%) and accounted for the highest proportion is fish (56.9%).
The study results are also relatively similar to the Channa lucius nutrition spectrum research in
Indonesia with the ratio from fry of 70.8 to 89.0%, crustaceans of 5.81 to 16.1% (Azrita and
Syandri, 2013)
7.30 % 6.30 %
14.7 %
56,9 %

14.8 %

fish
Crustaceans
Worms
Mollusks
Detritus

Figure 4.8: Nutritional spectrum (by weight) in the fish digestive tracts
4.5 Characteristics of reproductive biology of Channa lucius
4.5.1 Sexing Channa lucius
When observing many mature specimens of wild Channa lucius, we may see the males are
often dark blacker and more colorful than females. But the female have more patterns on the body
than the male. The color change characteristics of Channa lucius is similar to the one of female
Channa punctata in the breeding season, their sides become yellow (Dehadrai et al., 1973). During
the Channa lucius sexual maturity, the female often have big belly, soft dough; their genital spines
are big and blunt, round and rosy. The males have small belly, and their genital spines are sharp,
long and white.
4.5.2 Stages (S) of development of female gonads
Based on the six-level scale of gonads of Nikolsky (1963), Channa lucius ovarian in each
stage has the following distinguishing features:
- Stage I
In this phase, the fish gonads are immature with underdeveloped ovaries. It is only two white
and transparent slivers . The Oocytes in this stage include whole-cell and small ovum primary
oocytes. There are many different angles and close arrangement, big round core occupies most of
the cell volume and less basophilic to capture purple blue hematoxylin, while strong basophilic
cytoplasm captures pink eosin.
- Stage II
In the Ovarian at this stage appear many tiny blood vessels to feed the cells and ovarian
begin with pink, thin films and transparent ovaries. The size of the ovary is still small and only

accounts for 1/6 of the body cavity (Figure 4.11a). At this stage the fish have sexually mature
12


coefficient of 0.25±0.01%. The features of tissue cells at this stage largely contain the oocyte
cytoplasm of growth period and a number of cells in the nutritional growth period. The cells are
rounder than the ones in the synthetic core period and they are arrange closely together (Figure
4.11b).
a

b

Figure 4.11: a) ovaries S II, b) Ovum oocytes S II (40X)
- Stage III
a

b

Figure 4.12: a) Ovaries S III; b) Ovum oocytes S III (10X)
The Ovaries clearly increase in size, with straw yellow on the surface of the ovaries there are
many tiny blood vessels distributed evenly across the surface. Naked eye can see particles scattered
eggs in the ovary (Figure 4.12a). Individuals in this stage have sexual maturity coefficient of
0.7±0.32% and 1.06 mm diameter eggs (0.98 to 1.11 mm). The features of ovarian cytology at this
stage contain most of the cells in biomass growth period (Figure 4.12b).
- Stage IV
a

b

Figure 4.13: a) Ovaries S IV; b) Ovum oocytes S IV (4X)

The ovaries constantly increase size and many large blood vessels are distributed evenly across
the ovaries, the big egg particles, even and easily separate each egg beads (Figure 4.13a). Fish in
13


stage IV have coefficient sexual maturity reaching 1.27% and 2.88±1.18 mm diameter eggs (1.10 to
1.23 mm). Characteristics of ovarian cells at this time are mainly in the nutritional growth period and
maturity. Rounded oocytes, yolk particles stick around and catch dark pink eosin (Figure 4.13b).
- Stage V: This is the reproductive stage, the fish egg cells reach the largest size, the particles
now separate eggs and egg plates flowing into the environment outside the body when gently pressed
into the belly of the fish. This phase exists only in a very short time period.
- Stage VI: This is the completion of spawning stage when the fish ovaries shrivel, soft dough
structure, ovarian membrane furrow, and eyes can see a few big and yellow oocytes that spawners
residue (Figure 4.14a). In this period oocyte of nutrition growth is degraded and is reabsorbed, besides
there are still some reserves in cell growth period cytoplasm (Figure 4.14b).
a

b

Figure 4.14: a) Ovaries S VI, b) Ovum oocytes S VI (4X)
4.5.3 The development stages of male gonads
- Stage I: The fish sperms are undeveloped. At this stage gonads take the form of two small
pieces, transparent white and underneath the organ. In the chamber of stage I there are mainly
gonialblasts .
- Stage II: Sperm chamber of this stage begins lobed. Then the chamber is larger than the
one of stage I with transparent white. The fish have small gonads and the maturation coefficient
reach 0.076±0.03% (Figure 4.15a). At this stage there is cell proliferation in the number of
primary sperm cells. The sperm cells form clumps and are surrounded by a membrane called the
capsules (Figure 4.15b).
b

a

Figure 4.15: a) Sperm chamber SI, b) Histological organization in sperm chamber SI (40X)

- Stage III:
Sperm chambers are opaque white with divided lobes. On the surface of the chamber there
are many tiny blood vessels. Maturity coefficient of fish reach 0.198 ± 0.08% (Figure 4.16a). In
14


the gonad chamber of this stage the number of primary and secondary sperm cells is more than
that at stagee II and also appear sperms catching green purple (Figure 4:16b).
a

b

Figure 4.16: a) Sperm chamber S III, b) Histological organization in sperm chamber S III (40X)

- Stage IV:
Sperm chambers are slightly opaque white. When the sperm chambers are cross-cut, there is
liquid on the blade, but when we pat on the belly, the liquid will not run out. At this stage the fish
have matured coefficient reaching 0.533±0.17% (Figure 4.17a). Histological observation of
chamber organization at stage IV shows that the chamber consists largely of sperms catching blue
purple (Figure 4.17b).

a

b

Figure 4.17: a) Sperm chamber S IV, b) Histological organization in sperm chamber S IV (40X)

- Stage V : Sperm chambers become opaque white with glossy surface and more room than
the one at stage IV. Sperm chambers are reproductive status. Sperm chambers develop to reach
the maximum size and are in a state of reproductive ejaculation. At this stage the fish have
matured coefficient reaching 1.619 ± 0.80%, while we pat the belly of fish, liquid will run out.
- Stage VI:

a

b

Figure 4.18: a) Sperm chamber S VI, b) Histological organization in sperm chamber S VI (40X)

15


After spawning, the mass and size of sperm chambers decrease significantly, the surface
looks milky-colored, the surface is pale pink and sperm chambers become soft dough (Figure
4.18a). Inside the vas deferens are the empty capsules and a few leftover sperms (Figure 4.18b).
4.5.4 Maturity coefficient

GSI (%)

4.00
GSI cáFemale
cái

3.00

GSI cáfemale
đực

2.00
1.00
0.00
1

2

3

4

5

6

7

8

9 10 11 12

-1.00

Time (month)
-2.00

Figure 4.19: Variation of GSI coefficient of channa lucius

Coefficient CF.10-2

Figure 4:19 shows GSI of male and female Channa lucius are constantly changing over time,
the ratio of GSI female and male Channa lucius starts to increase from December last year and
reaches the pinnacle of female and male GSI in June respectively 1.68% and 0.53%. Lowest GSI
coefficient for female Channa lucius was 0.69% in November but the male fish was 0.15% in
September.
4.5.5 Condition Factor CF

1.200
1.000
0.800
0.600
0.400
0.200
0.000

CF
đực
CFcá
female
CF
cái
CFcámale
1

2

3

4

5

6

7

8

9 10 11 12

Time (month)

Figure 4.20: Condition factor (CF) of channa lucius
Figure 4.20 shows survey results indicate the CF of female Channa lucius ranged 0.842.10-20.864.10-2 and male 0.848.10-2-0.874.10-2. The CF of female and male were highest in June,
0.864.10-2, 0.874.10-2 respectively.
4.5.6 Seasonality and reproduction cycle
Via survey results ovarian female ratio reached stage III (33.3%) and IV (58.3% ) in May.
Meanwhile, in September, the female ovary at stage IV (11.1%), at stage III only 11.1% and the
female in stages I - II (70.2%) accounted for highest. Based on the rate of maturation and GSI
coefficient of female Channa lucius, we can identify spawning season thickness starting from 1
and peaking in June of the year.
16


4.5.7 The length of first maturity
1.0
0.9

0.8
0.7

P

0.6
0.5
0.4

P=1/(1 + e -0,30*(L-21,3958) )

0.3

n = 391

0.2

R = 0,9565

0.1
0.0
4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

L (cm)

Figure 4.22: Corelation between maturity ratio and length of female channa
lucius
1.0
0.9
0.8
0.7

P

0.6
0.5
0.4

P=1/(1+e -0,17*(L-21,3952) )

0.3

n = 478

0.2
R = 0,9721

0.1
0.0
4

6

8

10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

L (cm)

Figure 4.23: Corelation between maturity ratio and length of male channa
lucius
Figure 4.22, 4.23 shows analytical results have determined that the first average length of
maturity of female Channa lucius is 21.3958 cm thick (n = 391, R = 0.9565), and male fish is
21.3952 cm thick male (n = 478, R = 0.9721).
4.5.8 Fecundity
A survey of wild fish (W from 94-295g) showed that average absolute fecundity is 2,065 ±
640 eggs/fish ranging from 905-3,519 eggs/fish and it is equivalent with the study on Channa
lucius in Lake Singkarak Basin, east of Sumatera Indonesia. It is 1,996-2,539 eggs/fish (Azrita
and Syandri, 2013). Regression Correlation between absolute fecundity (F) and the fish weight (W)
17


according to the equation F = 102.47W0.5845 (R2 = 0.4631, n = 77) and this result is also consistent
with the research on Channa lucius distributed in flooded areas Lindung Jambi-Indonesia (Azrita
and Syandri, 2013).
4.5.9 Diameter of eggs
Over 35 samples of eggs observed in stage III and 42 ovarian samples in stage IV showed
that Channa lucius eggs are spherical, relatively round and the diameter of oocyte in stage III has
average size of 1.06±0.03 (0.98 to 1.11 mm) and 1.18 ± 0.03 mm (1.10 to 1.23 mm) in stage IV. It
is smaller than the diameter of Channa lucius distributed in lake Singkarak Basin, east of
Sumatera-Indonesia (Azrita and Syandri, 2013).
4.6 Growout of channa lucius
4.6.1 Environment in growout pond: pH (6.9-7.5), DO (4-6mg/l), temperature (28.1o
30.6 C

4.6.2 Rate of Channa lucius of sexual maturity in growout pond
The result of sexual maturity of Channa lucius for four month’s growout is presented in
Figure 4.25.
75.0 72.7

Rate (%)

80
70
55.6

60

50.0

50
35.7 35,7

40

41.7

38.5

35.7

30.8

Trash fish

30

Industrial
pellets

20
10
0
30/11/2011

31/12/2011

31/01/2012

28/02/2012

31/03/2012

Time (month)
Figure 4.25: Rate of sex-matrue females in growout pond
For treatments feeding industrial pellets reaching 72.7% and trash fish reaching 75.0%. In
each month’s growout the ratios of sexually mature females in treatment for industrial pellets are
lower than the ones in treatment for trash fish. This problem may be that industrial food is not the
right food for the species, although the levels of protein in the feed is of 39.1%, 5.4% lipid, NFE
28.5%. The study results showed that Channa lucius are totally capable of sexual maturity when
growout is in ponds with trash fish or industrial pellets, which is similar to black snakehead fish,
potted snakehead (Pham Van Khanh, 2003; Nguyen Huan and Duong Nhut Long, 2008).
4.6.3 Coefficient of sexually mature of female fish in growout ponds
Coefficient of sexually mature in growout period of 120 days with trash fish feed and
industrial pellets are shown in Table 4.7.

Table 4.7: Coefficient of mature individuals over the months growout
Treatment
Coefficient of mature over the months growout (%)
30/11/2011 31/12/2011

31/01/2012

28/02/2012

31/03/2012

trea 1 (trash fish)

1.34±0.42a

1.42±0.71b

1.64±1.47b

2.27±1.31a

3.61±1.10a

trea 2 (industrial pellets)

1.40±1.22a

2.40±2.01a

2.84±1.34a

3.01±1.37a

3.54±1.84a

* Values shown are means and standard deviations. The values in the same column with different
letters are different with statistical significance (P <0.05).
18


The research results have identified a number of mature coefficient (MC) of fish in two food
treatments which are increasing with time growout. However, the increase of females mature
coefficient in treatment feeding with industrial pellets treatments at the end of the growout is
somewhat slower than the increase of fish mature coefficient in treatment feeding with trash fish.
Despite differences in mature coefficient of 2 treatments with difference without statistical
significance (p> 0.05). From Channa lucius growout results above it is able to confirm that
Channa lucius can get normal sexual maturity in ponds with trash fish food or industrial pellet
with protein of 39.1%.
4.6.4 Indicators of female CF growout ponds
Findings also noted CF index of Channa lucius presented in Table 4.8.
Table 4.8: Evolution of the CF index of Channa lucius in growout ponds
Time

CF (with growth factor b=3.0376)

Trash fish feed
Industrial pellets
a
30/11/2011
0.0090±0.0011

0.0090±0.0008a
31/12/2011
0.0091±0.0010a
0.0090±0.0011a
31/01/2012
0.0091±0.0009a
0.0091±0.0011a
29/02/2012
0.0092±0.0010a
0.0093±0.0017a
31/03/2012
0.0093±0.0013a
0.0095±0.0008a
*Values in the table represent the mean and standard deviation. The values in the same row with
different letters have differences with statistical significance at (p <0.05).
Table 4.8 shows the value CF after 120 days of growout feed increases from the first month
to the following months and ranges from 0.90.10-2-0.93.10-2 (trash fish feed) and 0.90.10-20.95.10-2 (industrial pellets). The values of CF of females have the difference between the two
treatments, but the difference in each month without statistical significance (P>0.05).
4.6.5 Fecundity of Channa lucius in growout ponds
Fecundity of Channa lucius in growout ponds with trash fish feed and industrial pellets are
shown in Table 4.9.
Table 4.9: Fecundity of Channa lucius in growout ponds
Treatment
Fecundity
Absolute fecundity (egg/female)
Relative fecundity (egg/kg female)
a
trea 1 (trash fish)
5,764±1,580
41,951±7,820a

trea 2 (industrial pellets)
4,296±737a
42,106±7,201a
* Values shown are means and standard deviations. The values in the same column with different
letters have differences with statistical significance at (p <0.05).
Absolute and relative fecundity of fish in growout by trash fish and industrial feed is
different in mean values but no statistical significance (p> 0.05). Fecundity of Channa lucius in
Table 4.9 higher than the fecundity of Channa lucius (13,105 eggs/kg fish) in the wild (Section
4.5.8).
4.7. Stimulating Channa lucius to reproduce
4.7.1 Experimental exploration in Channa lucius reproduction
Experiment 1: Effect of HCG on the reproductive indicators of Channa lucius
After the injection 31:30 minutes, the female fish begin to spawn in treatment 1, but in the
other treatments the fish do not spawn. The offspring is presented in Table 4.10.
19


For HCG injection treatments on male with dose of 1,000 IU/kg and 500 IU/kg spawning
female with 66.7% rate, fecundity of 1,127 eggs .kg-1. Eggs into the environment do not
concentrate and do not fertilize.
Table 4:10: The fecundity indicators of Channa lucius with single dose of HCG
Criteria
Controlled
trea 1
trea 2
trea 3
HCG on male (UI/kg)
0
1.000
2,000

3,000
HCG on female (UI/kg)
0
500
1,000
2,000
Effective time (hour)
0
31:30±2:7
0
0
Rate of spawning fish (%)
0
66.7±57.7
0
0
Reality fecundity (egg/kg)
0
1,127±76
0
0
Rate of fertilizer (%)
0
0
0
0
Notes:ET: Effective time; F: Fecundity: trea: Treatment
Experiment 2: The influence of LH-RHa + DOM on criteria of spawning
Results of using LH-RHa + DOM injections for both males and females. The reproductive
indicators are presented in Table 4:11.

Table 4:11: The criteria of exploration fecundity of fertility stimulant LH-RHa + DOM
Criteria
Controlled
trea 1
trea 2
LH-RHa on male (µg/kg)
0
200
350
0
100+4
100+4
LH-RHa+DOM on female (µg+mg)/kg
Effective time (hour)
0
40
0
Rate of spawning (%)
0
33.3
0
Real fecundity (egg/kg)
0
1,417
0
Rate of fertilizer (%)
0
0
0
Notes: trea:treatment

Table 4:11 shows that fish do not spawn in the controlled treatment (controlled) no LH-RHa
injection and injection treatments LH-RHa 350μg/kg on males and 100μg injection 4mg LH-RHa
+ DOM/1 kg on females. But 200μg injection treatments LH-RHa/kg on males and 100μg
injection 4mg LH-RHa + DOM/1 kg on female, the rate of spawners was 33.3%. However, the
eggs into the environment are still not fertilized.
Experiment 3: Effect of HCG and Pituitary extracts on Channa lucius reproductive
indicators
The reproductive indicators in experiment HCG + PE are presented in Table 4:12.
Table 4:12: reproductive criteria in the exploration HCG + PE
Criteria
Controlled
trea 1
trea 2
trea 3
HCG on male (UI/kg)
0
1,000
2,000
3,000
HGC+ PE on female (UI+mg)/kg
0
500+1
500+1
500+1
Effective time (hour)
0
30:0±2:48
33:0±2:36
32:0±2:39
Rate of spawning (%)

0
66.7±57.7
100
100
Real fecundity (egg/kg)
0
1,563±212
1,780±218
1,685±104
Rate of fertilizer (%)
0
0
0
0
Notes: ET: Effective time; RF: real fecundity;C: Controlled, trea:Treatment, PE: Pituitary
extracts
In this experiment the females in the injectable HCG treatments are spawning. The fish
spawn in trea 1, trea 2, trea 3, respectively 66.7%, 100% and 100%. However, the reproductive
activity of females appears otherwise than in the wild such as: male and female are not paired, do
no make nest before spawning and fish eggs after laying out water are still separate, not
20


concentrated in clusters with yellowish color. Actual fecundity of fish in all the treatments are also
very low (1,563 to 1,780 eggs/kg female) and eggs laid out in the treatments were not fertilized.
Experiment 4: Effects of HCG + PE and reducing water pH over the channa lucius
reproductive indicators.
Results of stimulating Channa lucius spawning in cement tanks by combining HCG
hormones and PE and stimulating ecology by lowering pH to 5.5 to 6.0 aquatic environment are
shown in Table 4:13. Through Table 4:13 it is shown that the mother fish after injection of 33-40

hours at temperatures of 28,5oC spawn in the laboratory experiment. Injectable treatments for
female PE with 500UI+2mg/kg and males with HCG 2,000 IU/kg at a rate of 100% and 66.7% for
spawners in 3000 injected experimental UI/kg. It is more important that the fecundity of fish in
two treatments was high (20004-25582 eggs/kg female) ratio from 92.0 to 95.0% of fertilized
eggs and hatching rate reaches 82, 0 to 83.0%. However, experiment 4 shows that when injected
with HCG in males at high dose (4,000 IU/kg) or no HCG injections, the fish do not spawn.
Lowering pH 5.5 to 6.0 and increase the dose to the PE 2 mg/kg on females showed initial
production results very positively.
Table 4:13: The Channa lucius reproductive criteria when using HCG hormones in combination
with PE and decreasing pH (5.5 to 6.0).
Criteria
Controlled
Treatment 1
Treatment 2 Treatment 3
HCG on males (UI/kg)
0
2,000
3,000
4,000
HGC+ PE on females
0
500+2
500+2
500+2
(UI+mg)/kg
Effective time (hour)
0
40:0±3:28
33:0±4:14
0

Rate of fish spawning (%)
0
100
66.7±57.7
0
a
b
Real fecundity (egg/kg)
0
25,582±4.329
20,004±625
0
Rate of fertilizer (%)
0
95.0±5.0a
92.0±4.0a
0
a
a
Rate of hatching (%)
0
83.0±6.0
82.0±6.0
0
Notes: The values in the same column with different letters have differences with statistical
significance. (p<0,05).
4.7.2 Main Experiment: Stimulating Channa lucius with HCG + PE in condition of 5.5 6.0 pH.
Table 4:14: Reproductive criteria of Channa lucius with hormones HCG + PE and reducing water
pH (5.5 to 6.0) in the main experiments.
Criteria

Controlled
Treatment 1
Treatment 2
HCG on males (UI/kg)
0
2.000
3.000
HGC+ PE on females (UI+mg)/kg
0
500+2
500+2
Effective time (hour)
0
39:42±1:42
37:24±3:9
Rate of spawning (%)
0
83.3±38.9a
58.3±51.5b
Real fecundity (egg/kg)
0
26,765±2,122a
21,646±2,249b
Rate of fertilizer (%)
0
95.3±3.0a
93.0±2.0b
Rate of hatching (%)

0

82.6±2.7a

81.4±1.7a

Time of hatching
0
42:30±1:42
46:00±2:40
Notes: The values in the same column with different letters have differences with statistical
significance. (p<0,05).

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Fish spawn after injecting HCG + PE approximately 37-40 hours for females with
environmental conditions 28.5 oC, pH 5.5 to 6.0. Eggs have golden brown and float on water in
clusters of nests. The reproductive criteria are presented in Table 4:14.
Percentage of Channa lucius spawning in treatments 1 and 2 respectively 83.3% to 58.3%
and difference was statistically significant (p<0.05). However, individuals in the controlled
treatment do not spawn. In treatments 1 and 2 fecundity reality is relatively high, respectively
26,765 and 21,646 eggs/kg in female and differences have statistical significance (p<0.05). The
proportion of fertilized fish eggs in trea 1 (95.3±3.0%) is high and different with statistical
significance (p<0.05) compared with treatment 2. The rate of hatching in treatment 1 and
treatment 2 is respectively 82.6±2.7%; 81.4±1.7% and the difference was not statistically
significant (P>0.05). Thus, when stimulating Channa lucius to spawn, in addition to using
hormones as some other species of freshwater fish, reducing pH 5.5 to 6.0 should be considered.
4.8 Morphological characteristics of fish digestive tube of 2 to 30 days old Channa
lucius
4.8.1 The relationship between fish mouth size and prey size: The results showed a

positive correlation between the old days, the length of the fish with the open mouth. For Channa
lucius after hatching 2 days with an open mouth 0.52 mm (L = 7.53 mm) and 30 days of age is
2.79 mm (L = 29.6 mm).
4.8.2 The ratio between gut length and body length of the fish fry (RLG): Results of the
study showed that the gastrointestinal tract of Channa lucius fry stage to fry large fluctuates not
much and increases with age day. RLG of Channa lucius is around 0.44 to 0.67 (RLG <1). Thus,
in this stage Channa lucius is carnivores.
4.8.3 The morphological development of the digestive tract
On the 4th day of age (96 h) the yolk of the fish is spent most, and the end of the esophagus
swells to form the stomach, and intestines begin folding each piece. From 5-15 days of age,
stomach size increases with hollow bag, thick wall and U-shaped type. Guts tend to increase the
number of folds. On the 20th age, morphology of fish digestive tract changes in that stomach has
more clearly shaped pocket structure, the length of gut increases with folding into parallel sections
in the abdomen, and 2 cecums appear but they are very small.
4.8.4 Histological characteristics of the gastrointestinal tract in Channa lucius
a) oral cavity:

c

b
a

Figure 4.28: Oral cavity of 5 day old fish fry (10X): a) mucosa;
b) oral cavity; c) Esophagus (10X)
In stage of 4-day-old fish, it is able to distinguish oral cavity with other organs in the
digestive tract of the fish. Oral cavity of the fish is made up of a thin layer of squamous
epithelium of layer monomers. At 5 days old, appear mucus secreting cells and taste buds (Figure
4:28).
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b) Esophagus:
Figure 4.29 shows the tubular esophagus, esophageal wall has thick outer layer of
connective tissue, the middle layer of striated muscle layer, the innermost layer of the mucosa and
it starts folding on the 4th day. The change of the esophagus is by increasing expression of the
folds of the lining, the number of cup-shaped cells by arranging the epithelium along the
esophagus demonstrated in 14-day-old fish (Figure 4:29).

b
c
a

Figure 4.29: Transects of 14-day-old channa lucius esophageal
(40X); a) cabin of esophagus; b) glass –type cell; c) folds

c) Stomach:

c
a

e

b

d

Figure 4.30: Intersect of 20 day old fish stomach (40X):
a) stomach route; b) mucosa; c) submucosa; d) the
smooth muscle layer; e) layers of the pericardium

The stomach is formed on the 4th day of age due to a swollen digestive tube section.
Configuration of stomach is very simple, only a single layer of cylindrical epithelial cells and
gastric glands do not appear. In 14-day-old fish, the stomach has thick walls and is made of 4
layers of the pericardium, the smooth muscle layer, submucosa, mucosa and stomach route
(Figure 4.30). In 20-day-old fish, morphological stomach bag is shaped relatively large,
observation of stomach tissue specimens at this stage is obvious, and stomach is divided into 2
parts which are gastric glands and stomach muscles. Stomach route is straight tubular, glandular
cells are slightly rounded, with multiple sinus capillaries and blood vessels and it is an important
part of the stomach. They hold a very important role in the secretion of stomach translation to
support digest food. The formation of gastric glands is characteristic marking the complete
development of the digestive system in larval stage (Figure 4.32).
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b
c
a

Figure 4.32: Intersect of 20 day old fish stomach 10X):
a) stomach cavity; b) stomach muscle; c) stomach route.

d) Fish Guts: the structure of newly hatched Channa lucius guts is a straight tube
undifferentiated, and histologic specimen observation can distinguish 4th day old gut. The
structure consists of a single layer of epithelial cells cylindrical lined on a thin layer along the
length of the intestine. Intestinal epithelium of fish begins to have folds on the 4th day of age and
lipid vacuoles appear on the 7th day of age (Figure 4:34).

a

b

Figure 4.34: Vertical slice of 7 day old fish gut
(40X):a) Lipid vacuoles; b) Folds

4.9 Selection of Channa lucius feed in stage 2 to 30 days old
The analysis of food in the pond environment and food ingredients present in the digestive
system of Channa lucius from 2-3 days shows that the fish only select small-sized food like
Brachionus spp., Nauplius. Since days 4-5 food is Cladocera (Moina spp., Daphnia spp.,). It
begins to appear and stabilize in the gastrointestinal tract of individuals from the age of 6. The fish
choose Copepod on the 6th day (Eucyclops spp.) and this food group is selected stably from the
18th day onwards. In the last stage of experiments, small-size food are not chosen such as
Nauplius with E<0 from day 6 onwards, Rotifera with E<0 from the 18th day onwards.
Particularly Protozoa is not found in the digestive tract of the fish during the experiment.
4.10 Channa lucius nursery
4.10.1 Timing the replace of processed food in period of 4-30 day old fish
* Rate of suvival and growth
Results of fish survival rate after 30 days nursery at transforming PF treatments on 16th day,
13, 10, are respectively 93%, 83%, 37% and at transforming PF treatments on day 7, the fish die
100%, on 16th day of nursery (9 days after changing PF). Survival rate difference between
24