Performance of polypropylene and cotton sheet, as bacterial substrata, on water quality, growth and survival of carp (Cyprinus carpio Linnaeus, 1758) larvae in a recirculating culture system

An experiment was conducted to determine the efficiency of two kinds of substrata (Polypropylene and cotton sheet), as biofilter media on removal of N-compounds and fish growth in a recirculating culture system for a 6-week period. Rates of survival was significantly different between treatments(p < 0.05). The mean (± SD) initial individual weight of fish was 3.4 ± 0.20 g and the fish attained to 9.19 ± 0.53 and 7.79 ± 0.38g in treatments with cotton sheet and polypropylene, respectively at the end of experimental period. Concentration of total nitrogen, total ammonia-N and nitrate were significantly different (p < 0.05) between treatments at the end of the experiment. Concentration of total ammonia-N reached to 0.050 ± 0.0021 and 0.054 ± 0.0039 mg L-1 in cotton sheet and propylene treatments, respectively. The electro-conductivities were significantly different and attained to 970± 0.32 and 900 ± 51.3µmos/cm in treatments with cotton sheet and propylene, respectively, at the end of experiment(p < 0.05). It was concluded that cotton sheet, can be used as an efficient bacterial substrate or medium in a recirculating carp culture system.