Diet composition of several different species of fish
Introduction
Demersal fish species are commonly bottom dwellers of the sea. They are broadly found near the surface of the sea. Fishermen usually use trawl net to catch them.
Nevertheless demersal and pelagic fishes are a part of the food chain in their habitat.
Many marine populations such as benthos organism, coral fish and many more are sharing with the demersal or pelagic fishes in the same habitat to live. This will influence the sources of food that the fishes will take up. Then from study of the diet based on analysis of stomach contents of the fishes can provide information about food habits of fishes to gain a better understanding on trophic relationship among the fishes in Malaysia sea water ecosystem. The interaction of food web chain is useful in defining predatorprey relationship.
They are many fish family belong to demersal and pelagic fishes such as Ariidae,
Haemulidae, Lutjanidae, Rachycentridae, Sphyraenidae, Carangidae, Clupeidae. All of this fish family can find in the pelagic and benthos ecosystem water in Malaysia. Each of this fish species have they own different source of food. Basically there are depending on the feeding type either deposits feeder, suspension feeder, carnivore, or herbivore and so on. This also influenced by the type of the fish’s mouth. By looking at a fish’s body and mouth shape it can be determine what the fish feeding on. From the study of the feeding behavior of marine fishes is necessary for fish stock assessment and ecosystem modeling.
For example, methods of multi-species virtual population analysis (Sparre, 1991:
Bulgakova et al . 2001) and the ECOPATH II ecosystem model (Christensen and Pauly,
1993) need information on the dietary composition of fishes.
Nowadays they are several reports on dietary habits of marine fishes in Malaysia water. But the diet composition for the demersal fishes is still lacking compare with the pelagic fishes. For example, Sallehuddin et al . (2002) has studied stomach contain for
Grouper ( Epinephelus sexfaciatus ) and Che Zukifli (2002), has studied stomach content of six pelagic fishes off Economic Exclusive Zone in the South China Sea while Ogawa

(2002), studied the migration and feeding habits of the grouper Epinephelus bleekeri in
Merbok estuary . The latest study for this topic was the diet composition and food habits of demersal and pelagic marine fishes from Terengganu waters, east coast of Penisular
Malaysia, Z.Bachok et al . (2004).
The objectives of these studies to find out defining predator prey relationship because the data on diet composition are very useful in the creation of trophic models as tool to understand the complex demersal fish ecosystem (Lopez & Arcila, 2002), besides to know the contains of the diet composition in fish stomach. The second objective is to recognize the feeding habit and fish diet.
Materials and Methods
Demersal fish specimen was obtained from Pasir Gogok, Johor Lama and
Belungkor in Johor, Malaysia from January 2006 to March 2006. Ten species were selected that are Alectis indicus, Anadontosoma chacunda, Arius maculatus, Arius thalassinus, Hilsa kelee, Lates calcarifer, Lethirinus lentjan, Liza subridus,
Scomberereide tala and Siganus guttatus. Each species of the fish were keep in the box containing ice to slow any bacterial digestion process in the fish stomach and make it easier to identify prey. Then fish samplers were taken to laboratory for further analysis.
In the laboratory the total length, fresh weight and sex for each species were determined.
Individual stomach was removed from fish and placed in 70% alcohol to prevent any further digestion of the stomach content. Weights of full stomach were taken then the stomach content was removed from the stomach using laboratory scissor and weight of the stomach skin was taken. Contents were blotted dry on paper towels before counts and displaced volumes using the 1-L graduated cylinder. Identified all food items in the fish’s stomach then the total number, wet weight and frequency of occurrence of each prey item in the stomach of the fishes were recorded. The methods that will be use is by observing the specimen under light microscope and analysis all data by the statistical analysis.

Result
Results of the stomach content analysis for the ten selected fishes are shown in table 1 as percentage of weight in diet of ten selected fish species and table 2 shows the percentage of occurrence in diet of ten selected fish species. The result showed that anchovy covered 52 percent of the food item of ten species of fish. Digested food covered
30 percent, and both penaeidae and crustacean covered 9 percent. This also showed that the main food of ten selected species of fish were anchovy. There were four items of prey found in all of the sample and just the main food that exceed to one percent were shown as pie or bar chart (figure 1 to 5). Many of the food items that cannot be identified at all are names as digested food and some also were half digested were name as general name like unidentified crustacean, bivalve and penaeida. Only the anchovy that can be identified because not digested at all. The pie chart (figure 1) shows percentage of occurrence of food item for all the samples. The pie chart (figure 2 to 4) showed the weight of food items for each species of ten selected fishes. The bar chart of figure 5 shows the percentage of occurrence of each species and the table 1 shows every item of prey that are found in the stomach of each species in percentage. Some of the fish show no food content in their stomach and this is cause during the trawling time the fish doesn’t ate any food. Some also only have one food item like
Alectis indicus, Arius thalassinus, and Liza subridus.

Penaeidea
9%
Bivalva
0%
Crustacean
9%
Anchovy
52%
Digested food
30%
Figure 1: Percentage of Food Items that found in stomach of Ten Selected Fish Species
Digested food
47%
Crustacean
53%
Figure 2: Percentage of Weight of every item of diet of Arius maculatus

Digested food
37%
Anchovy
63%
Figure 3: Percentage of Weight of every item of diet of Lates calcarifer
Panaeidea
43%
Anchovy
57%
Figure 4: Percentage of Weight of every item of diet of Scombereroide tala

120
100
80
60
40
20
0
Alectis indicus Arius maculatus Arius thalassinus Lates calcarifer
Spesis ikan
Liza subridus
Panaeidea Bivalva Crustacean Digested food Anchovy
Scombereroide tala
Figure 5: Percentage of Occurrence for Diet of Ten Selected Fish Species
Conclusion
This study archives its goal to determine the percentage of occurrence of prey in ten selected fish species. From this we can know the prey relationship of each species based on its diet composition. The dominant prey for the ten selected species are as follows; anchovy, digested food, penaeidae and crustacean. The four item of food are the most important food source for each species and each species have their own diet composition.
References
Che Zulkifli, C.I. 2002. Diet of six selected species of pelagic fish from the East Coast of
Penisular Malaysia’s Exclusive Economic Zone (South China Sea). Procedding of Seminar, National Fisheries Symposium 2002. Fisheries Research Institute,
Department of Fisheries, Penang.
Z. Bachok et al . Diet Composition and food habits of demersal and pelagic marine fishes from Terengganu waters, east coast of Penisular Malaysia.