Effect of Pollution on the Length-Weight Relationship, Condition Factor and Heavy Metal Concentrations in Ethmalosa Fimbriata and Chrysichthys macropogon from Coastal Waters of Ilaje, Ondo, Nigeria

This study investigated the impact of pollution on the length–weight relationship, condition factor, and heavy metals on Ethmalosa fimbriata and Chrysichthys macropogon in the coastal waters of Ilaje Local Government Area, Ondo State, Nigeria. The study aimed to evaluate the health status of the fish and provide insight into potential environmental risks. Fish samples were collected monthly over four months (April–July) from four fish landing sites: Ayetoro, Bijimi, Idiogba, and Asumogha. The fish were caught using gillnets with mesh sizes ranging from 0.6 cm to 4.0 cm. Standard length and weight measurements were taken, and length–weight relationship parameters were determined through regression analysis, while condition factors were calculated to assess fish health. Results revealed that the mean total lengths of E. fimbriata ranged from 16.72±4.40cm (Bijimi) to 20.20±4.94cm (Idiogba), and weights ranged from 62.18±34.30g (Bijimi) to 92.78±52.31g (Idiogba). For C. macropogon, mean lengths ranged from 16.82±4.97 cm (Asumogha) to 19.19±6.53 cm (Idiogba), and weights ranged from 65.28±41.28g (Asumogha) to 94.94±57.49g (Bijimi). Condition factors for both species fell within 0.60–1.70, indicating fair to good health despite detectable levels of copper, cadmium, and manganese (Mn) in fish tissues. E. fimbriata in Ilaje shows hyperallometric growth, while C. macropogon displays an allometric growth pattern. The length–weight relationship exponent (b) values deviated from 3 in most cases, indicating allometric growth patterns. The accumulation of heavy metals suggests ongoing environmental contamination, which may have implications for fish productivity, ecosystem health, and food safety in the study area. Keywords: Fish, Pollution, Allometric growth, Coastal water