Effects of different feeding frequencies on the growth, plasma biochemical parameters, stress status, and gastric evacuation of juvenile tiger puffer fish (Takifugu rubripes)

Abstract

Tiger puffer fish (Takifugu rubripes)is one of the most economically valuable aquaculture species in Asia. However, farming tiger puffer fish at the juvenile stage has been greatly restrained by cannibalization caused by inappropriate feeding regimes, resulting in very high mortality and great economic loss, particularly in intensive recirculating aquaculture systems. Therefore, the feeding strategy should adapt to fish appetite, nutrition requirements and welfare in intensive aquaculture. A 60-day feeding experiment was conducted to evaluate the effects of feeding frequency on the overall health of juvenile tiger puffer fish. Fish were randomly assigned to four groups with different feeding frequencies using the same ration size per feeding. P1: two daily meals; P2: four daily meals; P3: six daily meals; P4: continuous diurnal feeding using a belt feeder. Fish in the P2 group exhibited optimal values for growth, including final weight, weight gain rate, specific growth rate, feed efficiency, and survival (P < 0.05), followed by those in the P3 group. The crude lipid content increased significantly with increasing feeding frequency (P < 0.05), indicating that high frequency feeding could accumulate higher body fat content. The apparent digestibility coefficients of dry matter, protein, and lipid were significantly lower for fish in the P4 group than for those in the other groups (P < 0.05). The total cholesterol, triglyceride, and glucose levels increased significantly with increasing feeding frequency (P < 0.05), indicating that high frequency feeding leads to excessive accumulation of dietary carbohydrates and lipids in juvenile tiger puffer fish. Fish in the P1 and P4 groups exhibited relatively higher antioxidant enzyme activities (P < 0.05), which suggested that low and high feeding frequencies cause oxidative stress in juvenile tiger puffer fish. A comparison of non-linear model parameters revealed that an exponential model best described the gastric evacuation rate of juvenile tiger puffer fish, with approximately half the meal passed within 3 h, which further confirmed that feeding intervals in four times/day may more closely align with the digestive physiological characteristics of juvenile tiger puffer fish. Overall, these results indicate that the best growth performance and physiological indicators can be achieved when fed at 4 times/day.