Effects of Monoculture and Polyculture Systems on Common Carp (Cyprinus carpio) Growth and Health in Earthen Culture Ponds

Abstract

Background and Objective: in Iraq, freshwater aquaculture is mostly practiced in earthen ponds, where farmers use a traditional rearing method of producing Cyprinus carpio in monoculture. Therefore, the primary goal of this study is to evaluate the growth patterns and some health-related characteristics of common carp in both monoculture and polyculture systems to assist fish farmers in increasing their production.

Material and methods: Six earthen ponds (2500 m²) at a private ‎fish farm were used as the site of the 6-month experiment. Three ponds were used to stock 1300 common carp (initial body weight of 35 ‎‎± 5 g) in monoculture, while the other three ponds were used for cultivating 1000 common carp, ‎‎150 grass carp, and 150 silver carp in polyculture. An artificial pelleted diet was given to common carp. Every month, measurements were taken ‎from each of the fish and rearing ponds for important water quality parameters, growth, feed ‎conversion ratio, and determining some biological and health parameters.

Results: The findings showed ‎that the water quality parameters (water temperature ‎22 to 30.1°C‎, dissolved oxygen ‎5 ‎to 6.9 mg/l‎, and pH‎ 7.2 to 7.7‎), were ‎all within the range that was appropriate for fish farming. When compared to monoculture, the common carp in polyculture had better weight gain, daily weight gain, and specific growth rate ‎ (2400 g, ‎‎13.33 g, and 2.35, respectively). Additionally, common ‎carp in polyculture showed a higher feed conversion ratio (1.57). Furthermore, the survival rate of the polyculture ‎is greater than that of the monoculture. The hepatic somatic index and condition factor, however, ‎did not show any significant effects.

Conclusion : In conclusion, common carp raised in a ‎polyculture system with silver carp and grass carp increase in growth and survival rates without ‎affecting their general health.‎