Effect of stocking density on the growth rates of Clarias gariepinus in a floating hapa system

Any aquaculture system needs constant supply of good quality water. In the arid zone of Nigeria this problem becomes more acute. This study therefore tries to rear fish is enclosure (net-hapas) suspended in outdoor concrete tanks to maximize the use of water and feed. About 350 fingerlings (of mean weight of 4.93g) of Clarias gariepinus caught in the same locality in Lake Alau ( Maiduguri, Borno State) were stocked in net-hapas (1 x 1x 1 m) at 25,50 and 100 fish/m3. Each treatment was duplicated the fish were fed three times a day on a formulated 40% protein balanced diet at 5% body weight per day. Batch weighing of the fish in each net-hapa was carried out every fortnight for body weight measurement. Water quality parameters such as dissolved oxygen, pH and temperature were measured weekly. The results of the fish growth and feed utilization efficiency were pooled for each treatment, computed and analyzed using one-way-analysis of variance (ANOVA) Mortality was highest in treatment 3 (100/m3) when compared with treatments I and 2 (25/m3 and 50/m3 respectively). This is mainly due to handling stress because of the long distance from Lake Alau 10 the NIFFR Zonal Station outdoor ponds (>45km) and the method of capture (Cast net). There were slight differences in mean final weight and food conversion of the fish at the end of the study but no statistical differences were found among the treatments (P