Effect of different exposure time of papain on adhesion and some reproductive indices of <i>Clarias gariepinus</i> (Burchell, 1822) eggs under semi-arid environment of Sokoto, north-western, Nigeria

Abstract

Egg adhesiveness can cause major problems affecting the hatchability of Clarias gariepinus. However, appropriate media for de-adhesion in Catfish eggs is not yet well established. In this study, the effect of the anti-adhesion properties of Papain enzyme (extracted from pawpaw fruit peel) on Clarias eggs was investigated in terms of non-stickiness of eggs, fertilization rates hatchability and fry survival. Milt and eggs obtained from African Catfish broodstock of the same lineage were used for induced breeding following standard procedure. 4g of eggs were subjected to four (4) different exposure times of Papain – 30, 60, 120 and 300 seconds – and compared against a control. Treatment efficacy was assessed by comparing the percentage of non-sticky eggs, fertilization, hatching and survival rate in the treatments and control. Exposure time of 30 seconds was found to be most effective in preventing adhesiveness in the eggs. Also, eggs subjected to 30, 120 and 300 seconds of papain exposure had the best hatchability (50.58±1.84, 53.91±4.53, 59.21±2.97). Survival rate was similar among the treatments and control, except for exposure time of 300 (81.66±7.15) seconds with significantly lower survival rate. For effective hatchability and survival of Clarias gariepinus eggs, exposure to papain at 120 seconds is recommended.