Several methodological concepts on fertilization pro cedures of eggs during induced breeding of Clarias gariepinus abound. This has caused some controversy among the cat fish farmers regarding the best choice of methodology to adopt for optimal hatchability during spawning. This study was conducted to evaluate the best procedure for eggs fertilization and optimum hatchability of Clarias gariepinus at a reduced cost and of conservation interest. Three aquaria treatment sets were established in triplicates to accommodate different fertilization procedures. The major water quality parameters that are of interest were measured using standard methods. The weights of the broodstocks were determined using digital weighing balance and female broodstock induced using synthetic hormone (Ovaprim) at 0.5ml/Kg. The male were dissected ventrally to remove the testes which were later cut open longitudinally to juice the milt. Two mililitres of the mil t was measured into three petric dish, and the two of the treatment were diluted with 5ml of normal saline solution. The fish was stripped after the response time, and 4g were stripped into three different clean petric dishes for fertilization. The eggs were differently fertilized with the graded milt (milt alone, milt mixed with 5ml saline, and milt mixed with 5ml saline). Ten mililitres of clean water was later added to the treatment mixed with 5ml normal saline. The incubation time and hatching period were recorded. The hatchling, degenerated eggs, and unhatched eggs were counted and recorded after 36 hours of incubation. All the water quality parameter fell within the NESREA recommended levels except dissolved oxygen, also all the measured water quality parameters were not differed significantly in the three treatments except the water t emperature that differed significantly. Likewise all the water quality parameters varied significantly in the three aquaria set-up during the incubation period. The results further revealed direct fertilization with milt to have the highest percentage hatchability and the least unhatched eggs percentage, while the treatment with mixed milt and subsequent addition of water to the fertilized eggs recorded the least hatchability and the highest percentage of unhatched eggs, thus direct shedding of milt on striped eggs should be encourage for optimal production.
Key words: Hatchability, hormone, broodstock, breeding, induced