Acknowledgement
The authors express deepest gratitude to Dr. A.O. Maluwa for his materials which were used for making the hapas as well as his tireless and timely assistance whenever needed. Many thanks should also go to Dr. J. Kango’mbe for his assistance. Authors are also very thankful to the Bunda Fish Farm staff led by Mr. Chaggwa, the Farm Manager and the Chief Technician Mr. Nyali for assisting with laboratory work.