Interrelationship of Temperature, pH, Dissolved Oxygen and Nitrogenous Wastes in Fish Culture Systems

Abstract

Frequent monitoring of water quality in fish culture systems is important to profitable operation of fish farming ventures. This study investigated how water quality parameters such as Temperature, pH, Ammonia, Nitrate and Dissolved Oxygen interrelate in fish culture systems. Water samples were collected from a concrete tank and an earthen fish pond in a commercial fish farm in Ibadan over a period of six weeks. Water source for fish culture, fish feeding rate and frequency were the same. Temperature, pH, Ammonia, Nitrate and Dissolved Oxygen (D.O.) were all analyzed in the water samples using standard methods. Relationships exist among the water quality parameters examined. There were variations of each water quality parameters among the weeks in the fish culture systems. The levels of the parameters determined were within the acceptable ranges for fish culture. Temperature had a negative correlation with pH and D.O. at r values of -0.61 and -0.53 respectively. Ammonia had a weak negative correlation with pH at -0.41 r value. Interrelationship between temperature and dissolved oxygen gave an equation which predicts D.O. as -0.911T + 32.57 with R2 value of 0.373. A multiple relationship among ammonia, temperature and pH is such that at R2 value of 0.58, ammonia can be estimated to be 7.42+0.31pH – 0.20T.