Effects of temperature and feeding frequency on ingestion and growth for rare minnow

Water temperature and feeding frequency are two important components in feeding strategy that directly affect the growth and physiology of fishes. The rare minnow (Gobiocypris rarus) has been cultured for decades in the laboratory as an experimental fish and is widely used in environmental science research. An 8-week factorial feeding experiment was conducted on juvenile rare minnows to investigate the interaction between water temperature (ambient, 20, 24, 28 °C) and feeding frequency (one, two, three meals per day) on growth performance, feed utilization, gut evacuation and adaptability to variable environmental conditions. Groups fed three times a day at 28 °C attained the maximum final body weight, followed by those fed two times a day at 24 °C. There was an obvious curvilinear relationship between specific growth rate and temperature. Increased temperature significantly promoted food consumption and growth rate, but there were no benefits on growth by feeding multiple times at temperatures of 18 °C or lower. Temperature and feeding frequency also affected gut evacuation rates: high temperature and frequency lead to fast evacuation. These results show that the optimal temperature and feeding frequency for rare minnow is 24 °C and two meals a day for maximal growth, feeding efficiency, and daily management. The findings also suggest that the rare minnow has the ability to rapidly adapt to changing culture conditions by adjusting physiological activities in the short term.