Evaluation of Neem Leaf Extract as a Prophylactic Treatment for Bacterial Disease in Catfish Juveniles in Abia State

Bacterial diseases represent a major source of mortality in African catfish hatcheries and juvenile rearing operations, and the development of plant-based prophylactic treatments offers a sustainable alternative to antibiotic use. This study evaluates the prophylactic efficacy of aqueous neem leaf extract (Azadirachta indica) at bath treatment concentrations of 0, 50, 100, and 200 mg/L against Aeromonas hydrophila infection in Clarias gariepinus juveniles at a hatchery in Umuahia, Abia State, South East Nigeria. Juveniles were bath-treated for 30 minutes at each extract concentration before experimental challenge with a standardised Aeromonas hydrophila suspension. Mortality was recorded daily for 14 days post-challenge. Surviving fish were assessed for gross pathological lesions and blood parameters including packed cell volume, haemoglobin, and total leucocyte count. Results showed that fish treated with 200 mg/L neem leaf extract recorded the lowest cumulative mortality (18%) compared to 62% in the untreated control group. Haematological parameters in the 200 mg/L group were closer to normal reference ranges for healthy Clarias gariepinus, indicating a reduced severity of infection. No mortalities were observed during the bath treatment period itself, confirming the safety of neem extract at the tested concentrations. The study supports the use of neem leaf extract as a cost-effective and locally sourced prophylactic agent for bacterial disease prevention in African catfish hatcheries in Abia State.

Keywords: neem leaf extract, Aeromonas hydrophila, prophylaxis, Clarias gariepinus, Abia State