Cyclical starvation and refeeding in order to induce compensatory growth were investigated in juvenile yellow mystus (Hemibagrus nemurus). The fish (7.12 ± 0.14 g initial body weight and 8.87 ± 0.04 cm initial length) were starved for one (1DPW), two (2DPW), three (3DPW) or four (4DPW) days per week and otherwise fed ad libitum, while the control group was fed every day (no starvation, 0DPW). The indoor experiments lasted six weeks and followed a completely randomized design (5 treatments  3 replications  10 fish per replication). Growth performance, feed utilization, specific activity of digestive enzymes, carcass composition and muscle quality were used to compare the treatment effects. The fish in the 3DPW group exhibited clear compensation for the reduced number of feeding days and had increased body weight towards the end of the experiment. However, this compensation was insufficient to match the specific growth rate in the control group that was fed to satiation daily. The 3DPW treatment also maintained feed utilization parameters, specific activities of protein-, carbohydrate-and lipiddigesting enzymes, carcass composition and muscle quality, relative to the 0DPW control group. The remaining treatments gave some inferior characteristics when compared to 3DPW and 0DPW; the ranking of these feeding treatments was unexpected within the studied period. These findings suggest that cyclical starvation for three days per week (3DPW treatment) and refeeding could be used for rearing juvenile yellow mystus. The intermittent feeding schedule scheme is useful for labor management in the aquaculture production of yellow mystus. However, since partial compensatory growth was observed in the 2DPW and 4DPW groups, as indicated by the compensation coefficient, prolonged experiments on the accelerated growth rate should be conducted in further studies.

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Mealworm larvae (Tenebrio molitor) are edible insects consumed in feed and food. In the current study, the optimal harvesting time of mealworm larvae for use as aquafeed was investigated during the ages of 30–90 days after hatching (DAH). Development of digestive enzymes, proximate composition, and in vitro protein digestibility using digestive enzymes from African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus), were used as criteria. The specific activities of pepsin and trypsin significantly decreased with age (p < 0.05) from the first harvesting time until 50 and 45 DAH, respectively, while steadiness in these enzyme activities was observed onwards. Chymotrypsin specific activity appeared constant across all harvesting times. The specific activity of amylase significantly decreased in the later stages of development, while cellulase exhibited a different pattern suggesting it has a major role in dietary fiber utilization relative to starch. Regarding proximate compositions of the mealworm larvae, the moisture and ash contents decreased significantly with age, while the protein content exhibited the opposite trend with the highest contents from 60 to 90 DAH. Crude lipid was generally fairly constant, but its lowest value was observed in the earliest stage. In vitro protein digestibility was not significantly different across all harvesting times for both fish species, except for the significantly decreased digestibility value at 65 DAH relative to 30 and 35 DAH for Nile tilapia. However, based on the economic benefits of time for growth increment and proximate chemical composition, approximately 60 DAH is proposed as suitable for harvesting mealworm larvae to be used in fish feed.