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This study is conducted to examine the impacts of different rearing temperature and diet variation on haematological and serum biochemical parameters on the juvenile Lutjanus malabaricus, a commercially important fish species in Malaysia. Fish (16-18 cm) were divided into eight treatments (4 temperatures × 2 diets) each with three replicates of five juveniles each. Fish were subjected to four different rearing temperatures (22, 26, 30 and 34°C) and fed with a commercial pellet and a natural shrimp diet. After 30 days of experimental period, blood samples were collected and transferred into two different tubes from each sample: One containing EDTA as an anticoagulant agent and the other without EDTA for serum collection. All the haematological and biochemical parameters in all the treatments were within the normal range. Changing temperature and diet led to a significant change (p 0.05). The fish reared at 26°C and 30°C had significantly higher values than those reared at 22°C and 34°C (p

This study aims to elucidate the gastric emptying process of clownfish fed on artificial diet using two gastric evacuation models and to determine the pepsin activity in the digestion process in relation to feeding time. Regression analysis was used to evaluate the adequacy of 2 models; Anderson’s [St = So(1-So(α-1)ρ(1-α)t)1/(1-α) + ξ ] and Grove’s model [St = (Soα – αKt)1/α ], in describing the gastric emptying rate. Grove’s model provided a better fit with higher r2 value, with the calculated parameters of maximum meal size at time 0 (S0) = 0.195 g and gastric emptying rate (K) = 0.0165 g h-1. There was no initial delay phase as predicted and the evacuation followed a curve. Pepsin activity in the stomach showed rapid responses to food intake, where activity was detected at 1 h after feeding and reached its peak at 2 h after feeding. Pepsin activity decreased since then until the 12th h after feeding where it reached the lowest point. An increase of pepsin activity was detected later, where a small boost was detected at 24 h after feeding to digest the remaining food item in the stomach before the pepsin secretion decreased and maintained at pre-feeding level. Fast response of digestive enzyme in stomach implied that clownfish is equipped to utilize infrequent and irregular meals effectively.

The effects of salinity on the gastric emptying time (GET) and absorption of nutrient along the alimentary tract of tiger grouper (TG) × giant grouper (GG) (Epinephelus fuscoguttatus × E. lanceolatus) hybrid were studied. Juveniles TG×GG hybrid grouper (10.0 ± 0.5 cm total length; 50.5 ± 2.0 g) were reared in different salinities (10, 15, 20, 25 and 30 parts per thousand (ppt)) and fed with commercial pellet diet during the 60-day experimental period. The fish were then slaughtered sequentially at different time intervals after initial feeding to obtain GET. Our results showed that low salinity (10-20 ppt) lead to a shorter GET in the hybrid grouper. The shortest and longest GETs were observed in 15 ppt (12 h) and 30 ppt (18 h) treatments, respectively. Apparent digestibility coefficient (ADC) using ash contents was measured to determine the absorption of nutrient in each treatment. The absorption of macronutrient in TG×GG hybrid grouper was increased as the salinity decreased. The highest absorption occurred in 15 ppt (72% protein, 75% lipid, 68% carbohydrate and 74% energy) while the lowest absorption occurred in 30 ppt (59% protein, 64% lipid, 34% carbohydrate and 55% energy). The findings of this study suggested that 15 ppt salinity facilitates faster digestion and maximize the nutrient absorption of TG×GG hybrid and may enhance the growth rate of this newly developed grouper species.