Fatty acid composition of freshwater fish tilapia, (Tilapia mosambica), barbus (Barbus carnaticus) and Varal (Ophicephalus) is determined by gas-liquid chromatography. Varal contained the highest amount of C sub(20:5) acid compared to other 2 spp. Of the odd-numbered fatty acids C sub(17) was the predominant fatty acid present. Palmitic acid was found to have a lower level in these fish compared to marine fish. Barbus recorded unusually high percentage of 23.3% of C sub(18:2) acid

Gopakumar, K.

Aquatic Commons

PART 
scm IFRC TEC NICAL 
f E SP 
f ES S ES 
K. GOP AKUMAR 
Central Institute of Fisheries Technology, Cochin-682011 
Fatty acid composition of freshwater fish tilapia, (Tilapia 
mosamhica), barbus (Barbus carnaticus) and Varal (Ophicephalus) 
is determi:1ed by gas-liquid chromatography. 
Var:ll contained the highest amount of c20:5 acid comp-
ared to other two species. Of the odd-numbered fatty acids 
c 17 was the predominant fatty acid present. Palmitic acid 
was found to be in a lower level in these fish species comp-
ared to marine fish. 
Barb us recorded unusually high percentage of 23.3% of 
c18 :2 Acid. 
lNTRODUCTIO:\J 
Tilapia (Tilapia mosambica), barbus 
(Bar bus carnaticus) and varal ( Ophicepha-
lus) are three major freshwater fishes of 
India. Extensive investigations were carr-
ied out by Pathak and Reddy (1962) on 
the fatty acid composition of Indian 
freshwater fishes. Gruger et a!. (1964) and 
Ackman (1967) have determined the 
fatty acid composition of a number of 
North American freshwater fishes. 
A comparative study was carried out 
to understand the differences in the fatty 
acid build up among these three species. 
The results are given in this paper. 
VoL 12 No. 1 1975 
MATERIALS AND METHODS 
Both tilapia and barbus were caught 
from the famous freshwater reservoir, 
Malampuzha, of Kerala. Varal was pur-
chased from the market in Cochin. 
EXTRACTION OF LIPIDS 
Lipids were quantitatively extracted 
from the fish samples with chloroform-
methanol mixture (2: 1 v jv) by the method 
of Bligh and Dyer (1959). The chloro-
form extracts were concentrated in a 
current of carbon dioxide and lipids dried 
and weighed in vacuum. 
PREPARATION OF METHYL ESTERS 
The lipids were saponified by the 
21 
Gopatiumar: Fatly acid composition of freslirvaier fislies 
Official Methods of the American Oil 
Chemists' Society. The fatty acids reco-
vend were esterified with methanol-HCI 
reagent. 
GAS-UQUID CHROMATOGRAPHY 
Gas-liquid chromatographic analysis 
were carried out on a gas-chromatograph 
F and M model 1609, equipped with a 
flame ionisation detector and a Honeywell 
strip chart recorder (3m V). A stainless 
steel column 0.9 m. X 4.8 mm. (6ft. X 
3/16 in.) packed with chromosorb W (45 
to 60 mesh) coated with 15% Diethylene 
Glycol Succinate (DEGS) was used. Nitro-
gen was used as the carrier gas. . 
The operating conditions were as 
follows: Column temperature 200°C 
' , 
injection port temperature, 300°C, detector 
port temperature, 300°C, nitrogen 120 
ml./min., hydrogen 35ml./min., air 350 
ml./min. 
Methyl esters of fish oils, diluted in 
chloroform, were injected with a Hamilton 
10fll microsyringe. The analysis was 
carried out at 8 X 1000 attenuation.· 
Fatty acids. of unknown samples were 
determined by comparison with the re-
tention times of reference standards as 
described by Gopakumar and M. R. Nair 
(1 972). The probable errors are for 
major components (5%), low to medium 
range components (1 0/~) and upto 50% 
for the minor components. 
RESULTS AND DISCUSSION 
Examination of the fatty acid com-
positiOn of three species of common 
freshwater fish, varal (Ophicephalus), tilapia 
(Tilapia mosambica) and barbus (Barbus 
carnaticus) showed that a variety of fatty 
acids are seen in them. Odd-numbered 
22 
saturated and monounsaturated acids 
are present in them, c 17 acids being the 
most predominating. · Varal contained the 
highest amount of polyunsaturated fatty 
acid c20 : 5 but c22 acids are found to 
be present in smaller levels, uniformly, 
in all the three species. This pattern 
seems to be quite characteristic of the 
fish in this region. 
Hilditch and Williams (1964) observed 
that triglyceride oils and lipids from 
freshwater fish, compared to those of 
marine origin, are richer in C] 6 and c 18 
fatty acids and lower in c22 and c 20 
acids. Tropical and subtropical freshwater 
species were found to contain low levels 
of c 22 fatty acids (Pathak and Reddy 
1962, Brener et al. 1961, 1963). 
Ackman (1967) reported that in four 
North American freshwater fish (sheepshead, 
tullibee, maria and alewife) both c16 
and c18 acids were higher than in marine 
species. Ackman in this study observed 
that total di- aDd tri-enoic acids were 
twice as high in freshwater oils as m 
marine oils and tetraenoic acids were 
three to four times high in freshwater 
oils. He also suggested that extension of 
these to marine type fatty acids C20 : 5w3 
and c 22:fw3 etc. is not normally obli-
gatory in freshwater fish. 
Barbus recorded unusually high per-
centage of c 18 : 2 acid. This was also 
confirmed by chainlength analysis of the 
oil by GLC after hydrogenation. 
The levels of CI8 : 2 and Cl8 : 3 
acids in varal and tilapia are in the 
limits usually observed in freshwater spe-
cies (Ackman 1967, Ito and Fukuzumi 
1963b). Fatty acid build up in varal 
showed a marine type pattern containing 
Fish. T echnol. 
Gopaltumar: Fatty acid composition of fresiirvater fisties 
TABLE 
FATTY ACID COMPOSITION OF FRESHWATER FISHES 
Fatty acid 
designation 
Saturated acids 
cl2:o 
cl3:o 
c14:o 
Crs:o 
cl6:o 
cl7:o 
C1s:o 
cl9:o 
Total 
Monounsaturated acids 
c12:I 
cl4:1 
ciS: I 
c16:l 
cl7:I 
cl8:l 
C2o:1 
C22:1 
Total 
Polyunsaturated acids 
c1s:2 
c18:3 
cl8:4 
C2o:2 
c2o:3 
c2o:4 
C2o:s 
('22:4 
C22:5 
C22:6 
Lipids, g./ lOOg. 
wet muscle 
Total 
VoL 12 No. 1 1975 
Varal 
1.1 
2.7 
2.6 
25.2 
2.5 
15.2 
49.3 
1.0 
0.4 
3.7 
3.9 
20.2 
0.4 
0.3 
29.9 
5.6 
1.0 
0.4 
0.4 
0.3 
11.0 
0.4 
1.6 
20.7 
1.8 
Name of Fishes 
Barb us 
-Weight per cent-
0.3 
0.1 
2.1 
0.4 
[8.5. 
1.4 
W.9 
33.7 
ifU 
0.7 
0.1 
4.9 
0.4 
25.1 
0.7 
LO 
33.0 
23.3 
3.6 
Ll 
4.2 
0.4 
0.6 
33.2 
2.2 
Tilapia 
4.7 
0.9 
29.1 
3.0 
5.4 
1J.7 
44.4 
{);9 
"0.5 
13:8 
0.~ 
:19.8 
{t8 
0.3 
37.§ 
4.1 
4.0 
(O.§i 
·ltii 
2.1l 
iL5 
10.4; 0.5 
1.8 
2.0 
as.1 
3.7 
23 
Gopa~unwr: Fatty acid comPosition of fresfiwater fisfies 
a higher percentage of c20 : 5 01.0 %) 
than to other two species, barbus and 
tilapia. This is because of the high phos-
pholipid content in the lipids of varal 
(total lipid content being 1.8% and phos-
pholipids, 0.8% by weight of the wet 
tissues). Palmitic acid was found to be 
in lower level in these three species of 
freshwater .fish relative to marine oils 
and C 18 acids in higher proportions than 
in marine oils. The key role of palmitic 
acid (C16 : 0) in saturated fatty acid me-
tabolism in marine depot fats has been 
wen explained by number of workers 
(Ackman 1967; Ackman and Sipos 1965). 
The percentage of palmitic acid (60 per-
cent of total saturated) is almost within 
the range of value of these marine and 
freshwater oils, proposed by them. 
ACKNOWLEDGEMENTS 
The author is grateful to Dr. R. V. 
Nair, Director, Central Institute of Fish-
eries Technology, for his permission to 
publish this paper and Dr. K. T. Achaya, 
Executive Director, Protein Foods and 
Nutrition Developrr.ent Association of 
India for giving facilities to carry out 
GLC analysis while he was the head of 
the division of Oils and Fats at Regional 
Research Laboratory, Hyderabad. He is 
also indebted to Dr. E. H. Gruger (Jr.) 
of Pioneer Research Laboratory, Seattle, 
24 
U. S. A. for his valuable suggestions andl 
correcting the manuscript. 
REFERENCES 
Ackman, R. G. and J. C. Sipos. 19650 
Comp. Biochem. Physiol., 15 : 445. 
Ackman, R. G. 1967. Comp. Biochen1. 
Physiol., 22 : 907. 
Bligh, E. G. and W. J. Dyer., 1959. Can. 
J. Biochem. Physiol., 31: 911. 
Brenner, R. R., 0. Mercuri, M. E. De 
Thomas and R. 0. Peluffo. 1961. 
The Enzymes of Lipid Metabohsm. 
(Edited by Desnuella P.) pp. 101-108. 
Pergamon Press, London. 
Brenner, R. R., D. V. Vazza and M. E. 
De Thomas. 1963. J. Lipid Res., 
4 : 341. 
Gruger, E. H., Jr., R. \;V. Nelson and 
M. E. Stansby. 1964. J. Am. Oil 
Chemists' Soc .. 41 : 662. 
Hilditch, T. P and P. N. Williams. 1964. 
The Chemical Constitution of Natural 
fats. Fourth Edn. Chapman and Hall, 
London. 
Ito, S. and K. Fukuzumi. 1963B. J. 
Japan. Oil Chenzists Soc., ll : 278. 
S. P. Pathak and B. R. Reddy. 1962. 
Biochem. J., : 618. 
Fish. Techno!. 


Fatty acid composition of three species of freshwater fishes

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Fatty acid composition of three species of freshwater fishes

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