Acute Toxicity of Malachite Green to Five Species of Freshwater Fish

Abstract

Static bioassays were conducted to determine the acute toxicity of malachite green to silver barb (Puntius gonionotus), Nile tilapia (Tilapia nilotica), Gunther’s walking catfish (Clarias macrocephalus), carp (Cyprinus carpio) and snakehead fish (Ophicephalus striatus). Gunther’s walking catfish was the most sensitive to malachite green (96-h LC50, 0.066 mg/l), and Nile tilapia was the most resistant (96-h LC50, 0.425 mg/l.) The results indicate that malachite green is highly toxic to fish. Uses of malachite green at 0.10-0.15 mg/l for therapeutic treatment of fungal infections and external parasites of fish could be toxic to some species.