Cephalic abnormality in nine mating groups involving Clarias gariepinus with cephalic abnormality, non Cephalic and Maiduguri origin were investigated to determine the level and the genetic basis of the occurrences and its aquaculture implication. The highest mean percentage survival in a Cephalic crossed with non cephalic group was 68.6% whereas the last mean percentage survival was 25.7% in the group of Maiduguri cross with Maiduguri parent. Cephalic abnormality was observed in the crosses with both female and male cephalic with a total frequency ranging from 0 % to 70.8. %. The least number of cephalic abnormality was 18.5% which involved a cross of non cephalic with cephalic, and the highest was 70.8%. This level of cephalic abnormality shows that the defect was hereditary. This result implies that, the genetic factor is a major contributor in the feature of cephalic abnormality in Clarias gariepinus
