Amino acids essential for the growth of eels anguilla anguilla and a japonica shigeru arai, takeshi nose, yoshiro hashimoto

Bulletinof the Japanese Society of Scientific Fisheries

38(7) 753-759 (1972)

Amino Acids Essential for the Growth of Eels,
Anguilla anguilla and A. japonica*
Shigeru

ARAI**, Takeshi

NOSE**, and

Yoshiro

HASHIMOTO***

(Received December 28, 1971)

Essential amino acids for the 2 species of eel, A. anguilla and A. japonica, were examined
by using an amino acid test diet.
Forty fish were grouped in each aquarium
and fed the
test diets for a period of 6 weeks.
In the both species, the fish fed diets deficient in each of
alanine, aspartic acid, cystine, glutamic acid, glycine, proline, and tyrosine grew as well as
those fed the complete amino acid diet.
The fish fed diets deficient in each of arginine,
histidine, isoleucine,
leucine,
lysine. methionine,
phenylalanine,

threonine,
tryptophan,
and valine failed to grow until the deleted amino acid was added to the ration.
It was thus
established that eels require the same 10 kinds of amino acid reported to be essential for
salmonids and others.

Ten amino acids have been shown to be essential for the growth of chinook salmon1),
sockeyesalmon2), rainbow trout3), and channel catfish 4) by HALVEDR
and his colleagues
withamino acid test diets. By examining the incorporation of 14C into amino acids after
intraperitonealinjection of [U-14C]glucose, COEEYet al.5) indicated that the plaice and
solehavea dietary requirement for amino acids similar to that of salmonids and channel
catfish.
In the previous paper6), one of the authors reported that methionine, threonine, tryptophanand valine were found to be essential and proline to be non-essential for the growth
of the Japanese eel, Anguillajaponica by using the amino acid test diet developed by HALVER7)
for salmonids. The results, however, were not so conclusive, since the test diet itself
wasnot so satisfactory for the growth of eels. This led us to study both the test diet and
feedingtechnique for eels and establish a far more reliable testing method8). By using
it, we examined the amino acids essential for the growth of 2 species of eels, A. anguilla
and A.Japonica. The results obtained clearly demonstrated that the both species of eel
requirethe same 10 kinds of amino acid as reported on the other fishes.
Materials

Experimental fish

and Methods

Elvers of A. Japonica were obtained in March 1971, from Kago-

shima Prefectural Fisheries Station and those of A. anguilla in April 1971, from a wholesale


754

dealer

of

freshwater

purified

casein-gelatin

ment

was

cm)

and

made

aeration
test

source
of

were
of

the

and

carboxymethylcellulose

fied

practically.

basal

weeks

for

thetized
in

diet

both

aquarium

Saturday

as

moist

eat

the

diet

diet

was

cation

by

with

reduced

of

out
The

eels

acid
in

each

and

and

diet
this

the

2 weeks.
fed

each

in

twice
diet

equal

Co.

Table

not

Ltd.
modi-

1 for

3 days

feeding

with

period
g after
fish

a day

was

being
were

This

made

6

anes-

grouped

except

extruded

the

the

nearly

was

feeding,

the

which

were

0.01

needle.
after

in

Ajinomoto

Forty

test

without

minutes

diet,
of

after

feeding

preliminary

nearest

were
pasty

eiperi-

supplied

experimental

of

Thirty

test

gelatin

leaving

other

simulated

previous

Table

* L-arginine.HC1

basal

to

syringe

was
Before

of

The

Fish

and

(20•~20•~

ingredients

weighed

The

25•Ž

a mixture

but

feeding

aquariums

mixture

other

the

liver

Sunday
into

eels

tank

easy

remainder

to

of the

time.

established

mixture

to

at intervals
diet.

it.

The

beef

of

minute.

product

japonica.

a day.

nylon

of

A.

was
w/v)

once

a 50-ml

casein

the

fed

loss
at

newly

a binder,

amino

experimental
were

from

replacing
as

of

noodle

diet

each

a

received

individual
%,

with

soybean,

start

in

acid

replaced

Tubifex,

anguilla.

kept

per

experiments,
of

the

heated
liter

a binder.

case

(1.2

they

siphoned

cellulose

growth

Each

as

on

A.

were

water

was

anguilla

the

in

a casein-amino

feeding

solution
for

when

fine

Test

tion

eels.

in

25•Ž
at

g

fish

of

used

of

omitted

in a urethane

each

and

the

on
diet

A.

start

0.6

0.4-0.7

acid-hydrolyzates

the

was

of

at

weight

and

well

rate

2 weeks

addition,

before

tanks

body

japonica

and

the

was

In

immediately

The

A.

casein-gelatin

and

in

Experimental

at
for

kept

order.

g in

chloride

kept

casein

were

methods

aquarium

they

amount

in

1.7

polyvinyl

each

protein

They

diet8)

testing

of

to

diets,

the

fish.

approximately

Feeding
50

live

with

was

amino

ingredients
that

work8)

1.

diet9)

and

of

acid

as

the

mixture,

untouched

the

differed

Composition

used

beef

only

liver

basal
adding
(Table

which

slightly

diet

modifi-

carboxymethyl1).

sustained
from

after

that

The
the
of

composiexcellent

the

amino

of the basal diet.

4 .0, L-histidine. HCI-H20 2.0, L-isoleucine 4.0, L-leucine 6.0, Llysine. HCI 5.0, L-methionine 2.0, L-phenylalanine 3.5, L-threonine 3.0, L-tryptophan
1.0, L-valine 4.5, L-alanine 4.5, L-aspartic acid , 7.5, L-cystine 1.0, L-glutamic acid 10.0,
glycine 5.0, L-proline 4.0, and L-tyrosine 3.0 g.
** U .S.P. XII Salt Mixture No. 2 with trace metals91.
*** Vitaminized cellulose powder . The amounts of vitamins added to the diet were same as
those reported by HALVER91.


755

acid test diet adopted for salmonids and channel catfish. Test diets were prepared by
deletinga single amino acid from the basal diet by replacing it with a-cellulose powder.
The diet was finally adjusted to pH 6.2-6.5 with 25 % NaOH.
Results

The average body weight at each weighing period and mortality
Table 2 for A. anguilla and in Table 3 for A. japonica.
Anguilla anguilla The experiment was conducted

are summarized in

from June 6 to July 20, 1971.

The fish on the diets deficient in each of arginine, histidine, isoleucine; leucine, lysine,

methionine, phenylalanine,

threonine,

tryptophan

and valine showed a loss of appetite

in 3 days and apparent loss of body weight at the end of 2 weeks.

Mortality was observed

in some groups, especially in the lysine- and valine-deficient ones.

Fig.

1.

Growth
complete

of

the

experimental

fish,

A.

anguilla

(-0-;

amino

As shown in Fig. 1,

acid-deficient

diet,

-•œ-;

diet).

the detrimental effects of depletion of some amino acids were apparent at the end of 4
weeks, and to all the groups of fish showing a retarded growth was then given the basal
diet for 2 weeks.

In the recovery test, the fish recovered their normal appetite within

3 days and showed a rapid growth.
in the 2-week recovery period.
amino acids, arginine,
threonine, tryptophan

histidine,

The percent body weight gain ranged from 19 to 49

These results clearly indicate that A. anguilla requires 10
isoleucine,

leucine, lysine, methionine,

and valine as essential for the normal growth.

phenylalanine,

On the other hand,

the eels receiving diets lacking each of alanine, aspartic acid, cystine, glutamic acid, glycine,
proline and tyrosine showed a growth comparable to that of fish on the basal diet, indicating that these amino acids are dispensable.




758
Anguilla japonica
1971.

The experiment

was conducted

from July 27 to September 6,

As shown in Fig. 2, the growth of eels was generally slow in the first 2-week period,

but much improved in the second 2-week period, probably due to acclimation to the amino
acid test diet.
ed in this case.

As mentioned above, the preliminary feeding with the basal diet was omittThe eels kept on the diets deficient in each of arginine, histidine, isoleucine,

leucine, lysine, methionine,

Fig.

2.

Growth
complete

of

the

phenylalanine,

experimental

fish,

threonine,

A. japonica

(-0-;

tryptophan

amino

and valine showed a

acid-deficient

diet

, -•œ-

diet).

remarkable loss of their body weight. The percent body weight loss ranged from 8 to
15% for the first 2-week period and 6 to 12% for the second period . In the recovery
test lasting for 2-weeks, the fish recovered their appetite within 3 days as in the case of A.
anguilla, and the percent increase of body weight was 19-32 % in the recovery, test. These
results clearly demonstrate that there is no difference in essential amino acids between
A. japonica and A. anguilla.
Discussion

By using the newly established testing method, the amino acids essentialfor the
growth of 2 speciesof eel, A. anguillaand A.japonica, wereclearlyrevealedto be the same
as required by salmonidsand channel catfish. It may be noteworthythat eels seemto
be much more sensitive to the lack of essential amino acids. A loss of appetitewas
recognizedin a period as short as 3 days, while in 2 weeks on salmonids1-3)and channel
catfish4). The recoveryof appetite in the deficienteels was also rapid, whenthe deleting

essentialamino acid was added to the ration.


Although serine and hydroxyproline

were not included in the basal diet, the eels

attained nearly the same growth rate on it as on the casein-gelatin
acids are therefore reasonably

classified as dispensable

for eels.

diet.

These 2 amino

In the previous worek6),

the eels receiving the glycine-deficient diet showed a growth apparently inferior to that of
the control.

In this experiment,

however, dispensability

of glycine was clearly demon-

strated in the both species.

Acknowledgement

This study was partly supported

by a grant from the Ministry of Education.

The

authors wish to express here their sincere thanks to Ajinomoto Co. Ltd. for the generous
supply of amino acids and also to Kagoshima
in collecting the experimental

Prefectural Fisheries Station for assistance

fish.
References

1)
2)
3)
4)
5)
6)
7)
8)
9)

3. E. HALVER,D. C. DELONO,and E. T. MERTZ: J. Nutrition, 63,95-105(1957).
J. E. HALVERand W. E. SHANKS: ibid., 72, 340-346 (1960).
W. E. SHANKS,G. D. GABIMER,and J. E. 14ALVER: Prog. Fish-Cult., 24, 68-73 (1962).

H. K. DUPREEand J. E. HA.LVER: Trans. Amer. Fish. Soc., 99, 90-92 (1970).
C. B. CowEY, J. ADRON,and A. BLAiR: J. Mar. Biol. Ass. U. K., 50, 87-95 (1970).
T. Nose: Bull. Freshwater Fish. Res. Lab., 19, 31-36 (1969).
J. E. HALVER: J. Nutrition, 62, 245-254 (1957).
S. ARAI,T. Nose, and Y. HAsmMoTo: Bull. Freshwater Fish. Res. Lab., 21, 161-178 (1971).
J. E. HALVER: J. Nutrition, 62, 225-243 (1957).