ABSTRACT 

Catfish — Tilapia  polycuRure in senhi-ifflensive fish grow out can be carried out with any of the two ob3cctives ill mind. Firstly, the objective can be to grow out tilapia in which case the tiiapa characteristics of raid multipiietion becoiiics a indranc to achieving the objective of grow out. This is because he pond is ovem ci owdc(! resulting in stunting of the fish with negative consequences because tilapia of  small size ditches very low prices. When iiiis happens, catfishes are iitirouuced as preuators to control tilapia population. Secondly, the cbjcctive of culture can be to grow out catfishes. In this case, the tilapia is introduced as part of a strategy to increase pond natural 100(1 production available fbi the catfish which are regarded as predominately carnivorous. The tilapia is still grown out Ibr sale even though the primary target is tiie catfish. Cw'reiit practices in both cases in a typical semi-intensive catfisn — tilapia poiycul(ure is thai, the catfish is expecied to prey on the tilapia. it has been found that the catfish umight lint be such aim effective control on tilapia population due to difficulty in establishing the optimal numerical ratio of predator to prey, establishing the optimal sizes of prey in comparism with predator size and timing of the predator nitroduchon (Balarin, 1979). Aso,

the catfish might not be so cffeeti'e in successfully preying on the tilapia

enough to significantly inciease cattish yieid. This is in addition to energy

losses that 1\loijld be incurred in pc -ursii (Fiogendoorn, 1983).

This study focuses on the second case of catfish - tilapia polycuhture

where the aim is to grovv out catuish using tiiaHa as part of pond nalural luau

for the catfish. in this study, the tilaiJLI would Dc harvested periodically and

incorporated into catlish suppicuIentary feed. This would be compared with

current practices in similar semi-intensive catfish — ti!apia polycuhure.