Physicochemical Conditions and Trophic State of Two Fish Ponds in Edo State

Several commercial fish farms are sited in Owan West, Edo State, Nigeria, because of the existence of numerous rivers. These farms are managed with little knowledge of water quality and aquatic productivity. A study of two earthen ponds (Pond 1 and 2) in Uhonmora, Owan West, was carried out from March to June 2015, to determine their physicochemical conditions and trophic state. Water samples were collected monthly from the ponds and analyzed using standard methods. Chlorophyll a was extracted with 10 % acetone. Trophic state was determined using the Carlsons trophic state index (CTSI) model. Data were statistically analyzed with GraphPad Prism Software. The range of the physicochemical parameters measured was within acceptable limits for pond fish culture. However, Pond 1 mean values were significantly higher (p less than 0.05) than Pond 2 for water level, dissolved oxygen, total dissolved solids, conductivity, total hardness and calcium. Pond 2 mean Chlorophyll a (3.300.81 g/l) was significantly higher than Pond 1 (2.300.24 g/l). CTSI values varied between 37.87 and 39.58 (oligotrophic) for Pond 1 and 39.18 to 44.19 (oligomesotrophic) for Pond 2. Oligotrophic state of Pond 1 despite its higher nutrient level may be attributed to the effect of duckweed infestation and poor management.