Sublethal Toxicity Effect of Chlorpyrifos on Growth Performance of the Indian Major Carp, Labeo catla
Deepika Bhosle *
Department in Bioscience, Mats University, Raipur, Chhattisgarh, India.
Ashish Saraf
Department in Bioscience, Mats University, Raipur, Chhattisgarh, India.
*Author to whom correspondence should be addressed.
Abstract
Labeo catla is a fast-growing, surface-feeding species widely cultured in reservoirs, ponds and rivers across India. Organophosphate insecticides become a major environmental concern because of their widespread application, high biological activity and proven toxicity to non-target organisms, particularly freshwater fish. Chlorpyrifos is one of the most commonly used broad-spectrum organophosphate insecticides. In aquatic environments, chlorpyrifos can persist long enough to cause chronic, sublethal exposure in fish populations. The present investigation was conducted during 2024-25 under controlled laboratory conditions at Bilaspur, Chhattisgarh, to evaluate the effects of sublethal exposure to the organophosphate pesticide chlorpyrifos on the growth performance of Labeo catla. Healthy juvenile fish of uniform size and weight were acclimatised and exposed to graded sublethal concentrations of chlorpyrifos (4.0, 8.0, 16.0, 32.0 and 64.0 ppb) along with a control for a period of 60 days, following a static-renewal bioassay under a Completely Randomised Design. Growth parameters, including initial and final length and weightgain, percentage gain and specific growth rate (SGR) on both length and weight basis were recorded and statistically analysed. Results revealed a clear concentration-dependent suppression of growth in Labeo catla. Final length declined from 12.01 ± 0.25 cm in the control to 9.95 ± 0.07 cm at 64.0 ppb, while length gain decreased sharply from 2.12 ± 0.24 cm (17.58 ± 1.66%) in the control to only 0.12 ± 0.07 cm (1.20 ± 0.67%) at the highest concentration. Correspondingly, length-based SGR dropped from 3.53 ± 0.40 % day⁻¹ in the control to 0.20 ± 0.11 % day⁻¹ at 64.0 ppb. A similar trend was observed in weight parameters, with final body weight decreasing from 18.65 ± 0.73 g in the control to 11.98 ± 0.15 g at 64.0 ppb. Weight gain declined from 6.87 ± 0.74 g (36.64 ± 2.52%) in the control to 0.27 ± 0.15 g (2.22 ± 1.25%) at the highest exposure level, while weight-based SGR decreased from 11.45 ± 1.23 to 0.45 ± 0.26 % day⁻¹. The pronounced reduction in growth indices at higher chlorpyrifos concentrations indicates severe impairment of feeding efficiency, nutrient assimilation and metabolic performance, likely due to pesticide-induced physiological stress and energy diversion towards detoxification processes. The study conclusively demonstrates that even sublethal concentrations of chlorpyrifos can significantly inhibit the growth performance of Labeo catla, highlighting the potential ecological and aquaculture risks associated with chlorpyrifos contamination in freshwater ecosystems. It is recommended to develop effective regulatory measures emphasising the need for cautious pesticide use to protect fish health and aquatic ecosystem sustainability.
Keywords: Chlorpyrifos, Labeo catla, growth performance, sublethal toxicity, specific growth rate, freshwater fish, organophosphate pesticide, aquatic pollution