HighlightsLight design is needed in recirculating aquaculture systems.A long photoperiod is beneficial to largemouth bass growth.Low light intensity is beneficial to largemouth bass growth.Abstract. In this study, recirculating aquaculture systems (RAS) were used to culture juvenile largemouth bass, and the effects of LED light intensity and photoperiod on the survival and growth performance of juvenile largemouth bass were studied. In the light intensity experiment, largemouth bass juveniles with an initial weight of 0.53 ±0.02 g were subjected to a two-month feeding experiment under two different light intensities: group A, at 0.5 W m-2 in the first month and 5 W m-2 in the second month; and group B, at 5 W m-2 in the first month and 0.5 W m-2 in the second month. The results showed that in the first month of the experiment, the growth rate of fry was faster in group A than in group B. After changing the light intensity, the weight of the fry in group B after one month of growth had exceeded and was significantly higher than that in group A. Based on the above experimental results, we conducted a photoperiod experiment. Largemouth bass juveniles with an initial weight of 0.56 ±0.02 g were cultured for two months under four different photoperiods (24L:0D, 16L:8D, 8L:16D, and 0L:24D). The light intensity of the four groups was 0.5 W m-2. The fry growth rate was fastest in the 24L:0D photoperiod group and slowest in the 0L:24D photoperiod group. The growth rate of the 24L:0D photoperiod group was significantly higher than that of the 0L:24D photoperiod group (p < 0.05). The final fry weight was highest in the 24L:0D group, followed by that in the 16L:8D group and 8L:16D group, with the lowest weight observed in the 0L:24D group (p < 0.05). Although the different light conditions in the two experiments had no significant effect on the survival rate of juvenile largemouth bass (p > 0.05), a low-intensity light environment with a continuous photoperiod during the juvenile largemouth bass culture process promoted growth and development. Keywords: Growth, Largemouth bass, Light intensity, Photoperiod, RAS.
The effects of carbon dioxide on growth performance, welfare, and health of Atlantic salmon post-smolt (Salmo salar) in recirculating aquaculture systems
