Occurrence and treatment of cracked-skull disease affecting Clarias spp. in homestead ponds in Nigeria

Abstract. Cracked-skull disease, previously unrecorded in Nigeria, affected fish in 80% of the homestead ponds investigated in this study. It was peculiar to mud catfish, Clarias spp., under intensive culture in urban Lagos, Nigeria. Male and female fish that were more than 10cm in length were equally vulnerable. The accessory respiratory structures were involved, but the liver, kidney, heart and the other internal organs were not. At its peak, the infection was characterized by a lateral crack in the skull, which resulted in death. Dip treatment in either 2-0ppm potassium permanganate or 0-5ppm formalin (with alcohol) for 30s day ¹resulted in 65-0 and 41-3% full recovery in 7 days, respectively. The implications of the disease for homestead fish culture are discussed.