The Impact of Nutrient Concentration (N:P) and Manure Type on Fish Polyculture

Abstract

Nutrient availability is considered to have a major role in controlling primary productivity. Therefore, an important aspect of successful aquaculture management in fish culture systems is making available basic nutrients, for example, phosphorous (P), nitrogen (N), and carbon (C) in optimal concentrations. The use of fertilizers in relation to pond productivity has been studied in order to develop better fertilization procedures under given environmental conditions. Many researchers from across the world have suggested different N:P ratios for optimizing fish production. The primary aim of this study was to understand the influence of nutrient quality and quantity on fish and primary productivity in terms of optimizing fish production. Two objectives of this study include evaluating the performance of pig and cow manures in terms of primary productivity and fish production; and understanding the influence of different N concentrations ranging from 1-2 ppm on fish production while P was maintained at 0.5 ppm. It was evident from this research that fish species nutrient-sensitivity to nitrogen concentrations ranging from 1-2 ppm was significantly different. The 1 ppm N:0.5 ppm P concentration was found to be the most suitable nutrient ratio for pond fertilization as significantly higher fish production and lower mortality were recorded in this treatment. In terms of plankton and fish production, pig manure was found to be significantly more effective than cow manure. Higher nutrient (>1 ppm N) concentrations negatively impacted zoo-plankton and zoo benthos development. Daily manure application would considerably reduce the organic load in the fish culture system, enabling more efficient use of nutrients for primary and secondary production.