Christopher Mulanda Aura

The Effect of Three Different Feed Types on Growth Performance and Survival of African Catfish Fry (Clarias gariepinus) Reared in a Hatchery

African catfish Clarias gariepinus is cultured as food fish, used to control overpopulation in tilapia ponds, and is grown as baitfish for the Lake Victoria Nile Perch fishery. Since the demand for Clarias gariepinus fingerlings is high, many farmers wish to specialize in fingerling production. In this study, the performance of three dietary feed types: freshwater rotifers with Artemia nauplii, freshwater rotifers with fish meal, and freshwater rotifers with maize bran, on the growth performance of African catfish fry, were done in a hatchery and they were raised in 9 glass tanks for a period of 21 days. Pearson’s correlation showed no relationship (𝑟=0.1; 𝑃>0.05) between growth and water quality parameters, but indicated a strong relationship between survival rate and total length between treatments (𝑟=0.85; 𝑃=0.02). Mean total length (TL) after 21 days were (A=15.003), (B=12.964), and (C=11.90) in mm for Treatments A, B, and C, respectively. Treatment A had the highest specific growth rate (SGR) of 6.475% day 1 followed by B (5.5320% day−1) and C (4.960% day−1). Results from this study demonstrate that after the 7 days of feeding using rotifers, Artemia is the best feed for increasing growth of Clarias gariepinus.

Haematological Response of African Catfish (Clarias gariepinus Burchell 1822) Fingerlings Exposed to Different Concentrations of Tobacco (Nicotiana tobaccum) Leaf Dust

The present study set out to investigate the haematological effects of tobacco leaf dust on African catfish, Clarias gariepinus, fingerlings, with a mean weight of 3.01 ± 1.25 g using “static renewal bioassay system” during a 120-hour bioassay exposure period. Water quality parameters such as pH and dissolved oxygen significantly decreased while total alkalinity and conductivity increased significantly in the exposed media, compared to the control test. Leucocytes counts increased significantly while erythrocytes counts decreased significantly with increasing concentration of tobacco dust. Packed cell volume significantly reduced with increase in the concentration of tobacco dust. Haematological examination showed that there was destruction of the erythrocytes production, and the concentration of haemoglobin was much lower in the exposed fish compared to the control depicting an anaemic condition. The results could provide baseline information for the safe limits of using tobacco leaf dust in fish ponds; hence 1.56 g L−1 concentration of tobacco leaf dust was recommended for pond preparation for Clarias gariepinus fingerling stocking. For better survival rates, the fish should only be introduced in the pond after three days of tobacco application.