EN
Aquatic ecosystem health is fundamentally linked to water quality, which is influenced by both natural processes and anthropogenic activities. The Calabar River, a critical freshwater resource in Nigeria, is increasingly threatened by pollution, habitat destruction, and climate change, adversely affecting its biodiversity and ecosystem services. Fish species, such as the Silver Catfish [Chrysichthys nigrodigitatus (Lacepède, 1803)], are widely acknowledged as effective bioindicators due to their sensitivity to environmental changes. This study investigates the potential of Silver Catfish as sentinels of environmental health in the Calabar River by assessing their morphometric and meristic characteristics alongside relevant physiochemical parameters of the river water. Over a three-month period, Silver Catfish specimens were collected monthly from Nsidung Beach, Calabar South. Morphometric traits, including body length and weight, and meristic counts such as fin rays, were analyzed in the laboratory. Concurrently, key physiochemical parameters temperature, dissolved oxygen, pH, turbidity, conductivity, total dissolved solids, and total suspended solids were measured to characterize water quality. Results revealed significant seasonal variability in morphometric indices, indicating potential environmental influence on fish growth and condition, whereas meristic features remained constant, suggesting genetic stability. Water quality parameters fluctuated, reflecting the impact of anthropogenic pressures and natural changes. The integration of these biological and environmental data highlights the suitability of Silver Catfish as effective sentinels for monitoring ecosystem health in the Calabar River. This study provides critical baseline data to inform sustainable management and conservation strategies aimed at safeguarding the river’s ecological integrity and supporting local communities reliant on its resources.