Post fingerings of Clarias gariepinus (size ranged and body weight, 8.0 – 10.5 cm and 12 – 16 g) respectively were exposed to sublethal dose of ethanolic extract of Piper guineense in a static bioassays to assess its histopathological effect on the fish liver. The findings revealed the destructive potential of P. guineense as an ichthyotoxic plant as exhibited by cell Hyperthrophy, Vascular degeneration, Vacuolisation, vascular congestion, granulation of eosinophilic cells and a remarkable degree of necrobiosis, the degeneration process leading to cell death.