Behavioural, Respiratory and Histopathological Effects of the Strobilurin Fungicide Picoxystrobin on Riverine Fish, Tilapia (Oreochromis niloticus)
Bharathi Selvi, R
PG and Research Department of Zoology, St. John’s College, Palayamkottai, Affiliated to Manonmaniam Sundaranar University, Tirunelveli – 627 010, India and Centre for Behavioural and Immuno-ecology, PG and Research Department of Zoology, St. John’s College, Palayamkottai, Tirunelveli – 627 002, India.
Suthakaran, M.R
Department of Zoology, Sri Paramakalyani College, Alwarkurichi, Tenkasi – 627 412, India.
Paramanantha Swami Doss. D *
Centre for Behavioural and Immuno-ecology, PG and Research Department of Zoology, St. John’s College, Palayamkottai, Tirunelveli – 627 002, India.
*Author to whom correspondence should be addressed.
Abstract
In this study, the toxicity of the fungicide was assessed using behavioural and histopathological effects in freshwater cichlids, specifically tilapia (Oreochromis niloticus). Picoxystrobin is a broad-spectrum systemic cereal fungicide belonging to the strobilurin class. Its mode of action involves blocking mitochondrial electron transport at the Qo site of complex III, thereby reducing ATP production and inhibiting cellular respiration. Tilapia was selected as the target species due to its global economic significance and ecological relevance. As one of the most widely farmed freshwater fish, tilapia plays a vital role in food security, aquaculture, and rural livelihoods. To evaluate the fungicide's toxicity, healthy and active tilapia fingerlings were exposed to low and high concentrations of the fungicide for 21 days. The mortality rate among the experimental fish was zero in the control group but increased in water treated with low- and high-concentration fungicides. In this study, fish exposed to various concentrations of Picoxystrobin exhibited a consistent and significant increase in opercular movement rate. The rise in opercular beats from control to higher concentrations was statistically significant (p = 0.05). Furthermore, oxygen consumption gradually decreased as Picoxystrobin concentration increased. Histopathological analysis showed that exposure to fungicide-contaminated water caused progressive alterations in target organs, including the intestine and gills. Overall, the behavioural, respiratory, and histopathological responses observed in this research emphasise the ecological risks of fungicide contamination in aquatic environments and highlight the need for stricter regulation of agrochemical residues in water bodies.
Keywords: Tilapia, pesticide, picoxystrobin, fingerlings, histology