Effect of Insecticide (Topstoxin) on the Reproductive Indices Clarias geriepinus (African Catfish)

Abstract

quatic ecosystems are increasingly threatened by agricultural runoff containing pesticides 
such as Topstoxin, a commonly used organophosphate. These contaminants pose a significant 
risk to the reproductive health of aquatic organisms, particularly fish species like Clarias 
gariepinus, which are important for aquaculture and ecological balance. In this study, a six
month static renewal bioassay was conducted to assess the chronic reproductive effects of 
sublethal Topstoxin exposure on C. gariepinus. A total of 200 juvenile fish were exposed to 
five concentrations of Topstoxin (0.00%, 1.50%, 2.50%, 3.50%, and 4.50%). Hormonal 
induction using Ovaprim was applied to evaluate the effects on gamete quality, sperm 
motility, milt volume, fertilization rate, hatching success, and larval viability. Data were 
analyzed using one-way ANOVA at a 95% confidence level. The results revealed significant 
dose-dependent declines in reproductive performance. Sperm motility was reduced by 65%, 
from 85% in the control group to 30% at the highest concentration (4.5 mg/L). Sperm 
abnormalities rose from 5% to 40%, and sperm volume declined by 58% (from 0.95 mL to 
0.40 mL). Fertilization rates dropped by 71%, from 85% in the control to 25%, and larval 
hatching success and survival were markedly impaired. In conclusion, chronic exposure to 
sublethal concentrations of Topstoxin significantly disrupts reproductive indices in Clarias 
gariepinus. These findings underscore the ecotoxicological risks posed by pesticide 
contamination in freshwater systems and highlight the need for stringent regulation and 
monitoring of pesticide usage near aquatic habitats