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*
(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,
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
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.
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
in a urethane
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.
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.
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,
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.
As shown in Fig. 1,
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,
The percent body weight gain ranged from 19 to 49
These results clearly indicate that A. anguilla requires 10
leucine, lysine, methionine,
and valine as essential for the normal growth.
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.
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,
and valine showed a
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.
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
These 2 amino
In the previous worek6),
the eels receiving the glycine-deficient diet showed a growth apparently inferior to that of
In this experiment,
of glycine was clearly demon-
strated in the both species.
This study was partly supported
by a grant from the Ministry of Education.
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
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).