Catfish aquaculture is the largest finfish aquaculture industry in the U.S. and plays a vital role in the U.S. economy. Both channel catfish (Ictalurus punctatus) and the hybrid between channel and blue catfish (I. punctatus x I. furcatus), are widely cultured, due to their fast growth rates at warm summer temperatures and broad tolerance of environmental conditions. However, because the overall physiology of ectothermic organisms is directly influenced by the environment, less is known about potential limitations of low temperatures on growth and physiological performance. Therefore, the effects of low water temperatures on growth, metabolism, and swimming capacity were evaluated in juvenile channel, blue, and hybrid catfish to guide culture practices .
Fish were acclimated to either 10°C or 20°C in two separate recirculating aquaculture systems and fed to satiation daily for 19 weeks. To measure growth, fish were weighed (nearest 0.01 g) and measured (nearest mm) at the start and end of the 19-week study. Standard metabolic rate (MO2 min) was measured using intermittent respirometry while maximum metabolic rate (MO2 max ) and swimming capacity (Ucrit ) were measured using a swim flume.
Weight gain was greater at 20°C than 10°C for all three fish types, with the largest weight increase occurring in channel catfish at 20°C. Hybrid catfish had the highest standard metabolic rate at both 10 and 20°C . At 10°C, channel catfish had the second highest standard metabolic rate followed by blue catfish, yet at 20°C blue catfish had the second highest followed by channel catfish. Swimming performance was a ffected by temperature, with little swimming capacity evident at 10°C. This study indicates low temperatures can greatly limit energy intake and associated capacity for physiological performance regardless of catfish type.