Full Length Research Paper

Acute toxicity of diazinon to the African catfish (Clarias gariepinus)

Olufemi Bolarinwa Adedeji¹*, Adetola Olamide Adedeji², Olanike Kudirat Adeyemo¹ and Samuel Adewumi Agbede¹

¹Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, Ibadan, Nigeria.

²Faculty of Veterinary Medicine, University of Ibadan, Nigeria.

*Corresponding author. E-mail: olufemi.adedeji@mail.ui.edu.ng,  oluadedeji2001@yahoo.com. Tel: 2348034917181.

Accepted 23 November, 2007

Pesticides and drugs used in agriculture and veterinary medicine may end up in aquatic environments and bioaccumulate in the food chain, thus posing serious problems for fauna and human health. The lethal concentrations of 50% of sample (LC₅₀) and 25% (LC₂₅) were determined using semi-static method. Eighty-four adult catfish were used for the toxicity study. Seven fish per test concentration in 2 replicates were exposed to varying concentrations of diazinon (0, 1.62, 3.24, 6.48, 12.96 and 25.96 ppm) in water. The effect of diazinon (LC₅₀) 6.6 ppm was further studied to determine the effect on behavioural, blood parameters and plasma biochemistry. The fish in the experimental group showed restlessness, increased reaction to exogenous stimuli, incoordination of movement and postural orientation before death. It is obvious from this study that diazinon negatively affects respiration and produces nervous signs with decrease acetylcholinesterase activities in fishes.

Key words: African catfish, Clarias gariepinus, acute toxicity, lethal dose.