Effect of initial stocking size of the predatory African sharptooth catfish (Clarias gariepinus) on recruits, growth performance, survival and yield of mixed-sex Nile tilapia (Oreochromis niloticus) in concrete tank culture system

Samwel Mchele Limbu,Huruma Fredrick Mgana,Evantuce Dominick Shirima,Hieromin Amon Lamtane,Amon Paul Shoko,Mary Alphonce Kishe-Machumu,Yunus Daud Mgaya

doi:10.1007/s40071-014-0093-3

Abstract

Prolific breeding and production of high percentage of recruits are main problems in mixed-sex Nile tilapia (Oreochromis niloticus) culture in earthen ponds. The current study assessed the efficiency of different sizes of African sharptooth catfish (Clarias gariepinus) in controlling recruitment in mixed-sex Nile tilapia cultured in tanks and its effect on growth performance, percentage survival and yield. Three treatments consisting of triplicate ponds stocked with mixed-sex Nile tilapia in monoculture and in polyculture with large (62.50 ± 3.26 g) and small (40.00 ± 2.68 g) African sharptooth catfish were fed on a 297.50 g kg−1 crude protein diet for 126 days. Results showed that, the number of recruits was significantly lower in larger African sharptooth catfish predator than smaller ones and monoculture of Nile tilapia. Polyculture with larger African sharptooth catfish resulted in significantly higher growth performance of Nile tilapia. Large African sharptooth catfish in polyculture reduced the amount of small, low-value recruits, while the yield of large and high value Nile tilapia was increased. This study revealed that fish farmers can reduce prolific breeding, obtain higher growth performance and produce larger size of marketable Nile tilapia by predominantly stocking ponds with large African sharptooth catfish predator of at least 60 g.

Highlights

Nile tilapia (Oreochromis niloticus, Linnaeus) is one of the most cultured species in the world (FAO 2012) providing major sources of animal protein and income (Chakraborty et al 2011; Yakubu et al 2012) in the majority of tropical countries (Lowe et al 2012)
This study revealed that fish farmers can reduce prolific breeding, obtain higher growth performance and produce larger size of marketable Nile tilapia by predominantly stocking ponds with large African sharptooth catfish predator of at least 60 g
Nile tilapia recruits stocked in monoculture tanks attained significantly higher mean body weights than those stocked in tanks with smaller African sharptooth catfish predator (p = 0.024)

Summary

Introduction

Nile tilapia (Oreochromis niloticus, Linnaeus) is one of the most cultured species in the world (FAO 2012) providing major sources of animal protein and income (Chakraborty et al 2011; Yakubu et al 2012) in the majority of tropical countries (Lowe et al 2012). Production of Nile tilapia is carried out in ponds, cages, tanks and raceways through mixed-sex monoculture, all-male monoculture and polyculture with predators. A. Kishe-Machumu Tanzania Fisheries Research Institute, Headquarters, P. O. Box 9750, Dar es Salaam, Tanzania

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