Panjab University Research Journal (Science)
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EFFECT OF PERIPHYTON AND SUPPLEMENTARY FEEDING ON GUT INDICES OF TWO BRACKISHWATER FISH SPECIES

Ashok Kumar, Anita Bhatnagar and S.K. Garg*

Department of Zoology and Aquaculture, CCS Haryana Agricultural University, Hisar - 125 004

*Corresponding author : gargsk@hau.nic..in

Abstract
Present communication deals with the food and feeding habits of two aquaculturally important brackishwater fish species (Oreochromis niloticus L. and Etroplus suratensis Bloch) grown in ponds provided with additional substrate for the development of periphyton. Two controls (Control 1 with supplementary feeding and control 2 with no additional substrate and no supplementary feeding) were maintained for comparison. The gut content analysis have revealed that irrespective of the treatments, O. niloticus mainly depended on vegetable matter and is thus a herbivore, whereas E. suratensis appears to be omnivorous as well as deterivorous. High values of RLG and DSI in O. niloticus and low values in E. suratensis further confirm the differences in feeding habits of these two fish species. Values for forage ratio indicated Coelastrum, Closterium and Cladophora are the preferred food items for O. niloticus confirming its herbivore nature. However, the values of forage ratio for E. suratensis indicated that Navicula, Synedra and Coelastrum are the preferred food items and in addition to this forage ratio values (1.79) for zooplankton were also high, indicating that E. suratensis is an opportunistic omnivore.

Key words: Gut indices, periphyton, RLG, DSI, pearlspot, nile tilapia, supplementary feeding