The study is on ichthyotoxic activity of Morinda lucida leaf on African catfish, Clarias gariepinus. The work shows that introduction of Morinda lucida leaf extract into the aquarium resulted in death of the fishes. Increase in concentration of the extracts lowered the survival rate of the fishes. The aqueous extract has the LC50 of 8.42 mgdm-3 while that of the ethanol extract is 9.51mgdm-3 showing that the aqueous extract is more toxic to the African catfish.