Phytoplankton and Food Selectivity in Nile Tilapia Reared in Earthen Ponds under Monoculture and Polyculture with African Sharptooth Catfish

By : Athanasio Stephano Mbonde , Samwel Mchele Limbu , Yunus Daud Mgaya , Amon Paul Shoko

Page No: 15-38

Abstract
Phytoplankton availability is one of the most important biotic factors affecting the successful culture of Nile tilapia (Oreochromis niloticus, Linnaeus) in semi-intensive ponds. The present study investigated phytoplankton composition, abundance and food selectivity in Nile tilapia Oreochromis niloticus (Linnaeus, 1758) reared in monoculture and polyculture system with African sharptooth catfish Clarias gariepinus (Burchell 1822) in earthen ponds. Water samples and stomachs of 144 O. niloticus were collected from respective pond systems for examination of phytoplankton composition and abundance. The obtained phytoplankton species in water and stomachs were used to determine food selectivity of O. niloticus. The results showed significantly higher Chlorophyceae in polyculture than monoculture ponds. The gut contents of O. niloticus from both systems were mainly composed of Bacillariophyceae, Euglenophyceae and Cyanophyceae and detritus and insect remains. Bacillariophyceae, detritus and insect remains were selected as food by O. niloticus cultured in both systems. Findings from this study show that, under monoculture and polyculture pond systems, O. niloticus exhibit selective feeding consuming more Bacillariophyceae, detritus and insect remains.

Authors :
Athanasio Stephano Mbonde
Tanzania Fisheries Research Institute, P.O. Box 90, Kigoma, Tanzania
 
Samwel Mchele Limbu and Yunus Daud Mgaya
Department of Aquatic Sciences and Fisheries Technology, University of Dar es Salaam, P. O. Box 35064, Dar es Salaam, Tanzania

Amon Paul Shoko
Tanzania Fisheries Research Institute, Headquarters, P. O. Box 9750, Dar es Salaam, Tanzania.