Impact of commercial probiotics on growth parameters of European catfish (Silurus glanis) and water quality in recirculating aquaculture systems

This study aimed to establish the impact of commercial probiotics on European catfish growth parameters and water quality in recirculating aquaculture systems. For the study, the European catfish were placed in two tanks with 45 fish in each tank. Average body weight and length at the beginning of the study were 133.0 g and 27.0 cm, respectively. Rearing conditions and feeding regime were identical, and the only difference was that 1 ml of commercial probiotics was poured into the water of one experimental tank every other day. The experiment lasted for 42 days. Weight and length were measured every 2 weeks. After each measurement, European catfish growth parameters, feed conversion ratios, and feed efficiency were established. After the end of the study, it was established that there were significant differences between specific growth speed, daily growth index, feed conversion ratio, and feed efficiency (P < 0.05) for the fish reared in two experimental groups. Statistically significant differences in the water parameters were established among ammonia, nitrite, and dissolved oxygen concentrations (P < 0.05). Differences in temperature, nitrates, and pH were statistically insignificant. The results of this study showed that commercial probiotics can be used in the European catfish culture to enhance water quality, feed efficiency, and growth performance.