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Simple Summary Fish are influenced by their surroundings. We investigated the effect of water temperature ranging from 26 °C to 32 °C on the growth performance and gastric emptying time (GET) of commonly cultured African catfish Clarias gariepinus fingerlings. Water temperatures between 26 °C and 32 °C were satisfactory for the growth of African catfish fingerlings, with GET observed between 10 and 16 h. Our experiment provides baseline data of the effects of water temperature on the culture of catfish. Abstract The present study was carried out to analyse the effect of water temperature on two components: (1) growth performance, and (2) gastric emptying time (GET) of African catfish Clarias gariepinus fingerlings. After 70 days, it was observed that experimental temperatures had no significant effects on the growth performance parameters, except for food conversion ratio (FCR) and food conversion efficiency (FCE). GET observation through X-radiography denoted that the shortest GET (10 h) was observed in fish reared at 32 °C and the longest GET (16 h) was observed in fish reared at 26 °C. The rapid digestion rate coincides with the FCR and FCE obtained in this study. Considering the limited scope of our study, more extensive studies on the impact of water temperature on other fish physiological parameters should be pursued. A better understanding of this research topic would be beneficial for the growth of African catfish fingerling aquaculture.

Laevistrombus canarium (Linnaeus 1758) or the dog conch is a highly important fishery species with great potential for introduction into aquaculture. The present study evaluates food consumption and assimilation by the adult conch at different temperatures (i.e. 22°C, 26°C, 30°C and 34°C). The conchs were acclimated for one week in stocking tanks with well-aerated seawater of 30 PSU salinity and at ambient temperature of 26°C. Prior to experimentation, the gastric emptying level of the conchs were standardized by allowing them to feed till satiation, followed by 24 h starvation. Ten similar sized aquaria (20 x 15 x 15 cm) were used, each containing one individual conch. Each conch was provided with similar quantity of food (~ 102.13 ± 0.45 mg of sinking pellets) and they were allowed to feed within a 24 h period. The food consumption rate for adult conchs was significantly different (p

Elevated ocean water temperature influences the physiological properties of fishes. This study is expected to characterize the oxygen consumption rate (OCR) and gill morphology in different temperature in hybrid grouper, tiger grouper × giant grouper (TGGGH). TGGGH specimens were distributed into four temperature groups starting from 22, 26, 30 and 34 °C within a recirculatory system under controlled conditions for 30 days in triplicates. Intermittent flow respirometry was directed to distinguish the impact of temperature on the OCR, and scanning electron microscopy was conducted to observe the gill morphology. Results indicated that the OCR of TGGGH increased significantly from 22.98 ± 1.16 mg O2 h−1 to 37.08 ± 1.56 mg O2 h−1 when temperature increased from 22 to 34 °C. Values of respired energy (RE) increased from 456.35 ± 11.41 Jh−1 at 22 °C to 737.88 ± 3.79 Jh−1 at 34 °C. Meanwhile, values of temperature quotients (Q10) were maximum at 22 °C–26 °C and minimum at 26 °C–30 °C. The favored temperature assessed from Q10 was between 26 °C and 30 °C. Gill lesions were significantly observed at 22 °C and 34 °C. The outcomes proposed that this fish species may neglect to maintain sufficient O2 uptake in future atmospheric situations. Thus, optimum oxygen consumption is required for maintaining the TGGGH in aquaculture environment.

Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32 degrees C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.

Rising of temperature in conjunction with acidification due to the anthropogenic climates has tremendously affected all aquatic life. Small changes in the surrounding environment could lead to physiological constraint in the individual. Therefore, this study was designed to investigate the effects of warm water temperature (32 °C) and low pH (pH 6) on physiological responses and growth of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) juveniles for 25 days. Growth performance was significantly affected under warm water temperature and low-pH conditions. Surprisingly, the positive effect on growth was observed under the interactive effects of warm water and low pH exposure. Hybrid grouper exposed to the interactive stressor of warm temperature and low pH exhibited higher living cost, where HSI content was greatly depleted to about 2.3-folds than in normal circumstances. Overall, challenge to warm temperature and low pH induced protein mobilization as an energy source followed by glycogen and lipid to support basal metabolic needs.

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.

In this study we analyzed the effects of water temperature and diet on the growth properties and gastric emptying period of juvenile Malabar blood snapper (Lutjanus malabaricus) over a 30 day experimental period. Fish were collected from a local hatchery of Pulau Ketam, Selangor, Malaysia and immediately transferred to flow-through sea water system and subjected to four different temperatures (22, 26, 30, and 34 °C) and two diets (formulated pellet and shrimp). Body weight gain, food consumption, food conversion ratio, food consumption efficiency, specific growth rate, relative growth rate, daily growth rate, and gastric emptying time were significantly influenced by temperature and diet (P

Hybrid grouper (Epinephelus fuscoguttatus [TG] × E. lanceolatus [GG]) juveniles were evaluated in terms of their blood hematology and biochemical levels after 60 days of exposure to different temperatures (22 °C, 26 °C, 30 °C, and 34 °C) in triplicate (20 fish/tank; body weight 200 ± 15 g; length 22.5 ± 1 cm). The fish were fed daily with commercial pellets (42% protein, 9% ash, and 11% lipid) or shrimp (42% protein, 9% ash, and 11% lipid). Results showed that the blood hematologic parameters of the fish fed with shrimp at 26 °C were significantly better than those at other temperatures. The lowest stress level measured in terms of glucose (26 ± 10 mg dL−1) and cortisol concentrations (0.5 ± 0.1 ng mL−1) after 60 days of the experiment were observed in the fish fed with shrimp at 26 °C compared with those fed with other diets and at other temperatures. Overall, the TGGG hybrid showed the highest red blood cell and total protein counts in fish fed with a shrimp diet at 26 °C, which were healthful and less stressful conditions. Thus, the health of TGGG hybrid fed with shrimp was better than that of fish fed with other diets and at other temperatures. These findings would be useful for further studies on the management of the TGGG hybrid to increase production. Keywords: Aquaculture, Hematology, Cortisol, Grouper, Temperature

The effects of temperatures (22, 26, 30 and 34 °C) and diets (commercial pellet and shrimp) on the growth properties and gastric emptying time (GET) of the tiger grouper × giant grouper (TGGG) hybrid were analyzed over a 30 day experimental period under controlled laboratory conditions. Food consumption (FC), food conversion rate (FCR), specific growth rate (SGR) and GET were significantly influenced by temperature and diet type. The highest mean SGR (1.00% BM day−1, p 0.05) were observed between any of the groups at 22 and 34 °C fed on either the shrimp or the pellet diet. The lowest statistically significant (p

In this study we aimed to analyze the effects of water temperature and diet on the length-weight relationship and condition of juvenile Malabar blood snapper Lutjanus malabaricus over a 30-d experimental period. The experiment was conducted in the laboratory using a flow-through-sea-water system. The fish were subjected to four different temperatures (22, 26, 30, and 34 °C) and two diets (commercial pellet and natural shrimp). Fish were fed twice daily. L. malabaricus exhibited negative allometric growth (b3) at 30 °C fed with shrimp diet, which indicated that fish weight increases faster than their length. The rest of the temperatures represented negative allometric growth (b

The newly developed hybrid grouper: tiger grouper (Epinephelus fuscoguttatus) × giant grouper (Epinephelus fuscoguttatus) (TG×GG), has a high resistance towards different environmental condition (eg. in euryhaline environment) due to its genetic improvement. This study aims to investigate the effects of different salinities (10, 15, 20, 25 and 30 ppt) on the gastric emptying time (GET) of the TG×GG hybrid grouper juveniles. The fish were fed with commercial pellet over a 30 days experimental period under controlled laboratory conditions. The GET was determined by X-radiographic method, using barium sulfate (BaSO4) as an inert food marker. The X-radiography images showed that the shortest GET (12 h) was observed in the 15 ppt group, whereas the longest GET (18 h) in 30 ppt group. The results suggests to culture TG×GG hybrid grouper juveniles in 15 ppt with commercial pellet diet as this salinity proliferates faster digestion process which may contribute faster growth rate of this important fish species. Overall, these findings would be useful for the betterment of TG×GG hybrid grouper aquaculture which will eventually boost up the production of this newly developed hybrid grouper species.

Increasing carbon dioxide (CO2) in the ocean are predicted to affect vital physiological functions and possibly reduce growth of marine fish. Yet, studies on the impacts on marine fish with the increasing CO2 is still limited. Therefore, this study aimed to explore the elevated CO2 effect on the growth and welfare (condition factor, blood parameters, stress analysis, gill histology) of newly developed commercially important marine fish, tiger grouper (Epinephelus fuscoguttatus) × giant grouper (E. lanceolatus) hybrid or TGGG. TGGG juveniles were exposed for 120 days in a laboratory condition of CO2 groups: 390 μatm (control-current CO2), 610 μatm (moderate) and 1010 μatm (high) consistent with projections for CO2 concentrations in the ocean over the next 50–100 years. The experiments were done in triplicate (20 fish/tank; N = 180, total length = 20.0 ± 0.5 cm, weight = 94.0 ± 3.0 g). Results showed that the lowest specific growth rate (SGR) (0.65 ± 0.05% day−1) and condition factor (1.12 ± 0.01) were observed in high CO2. Unfavourable blood haematological and biochemical parameters were observed in high CO2 group. The highest stress level measured by glucose (102 ± 8 mg dL−1) and cortisol concentration (1.0 ± 0.1 ng mL−1) were also observed in the high CO2. Gill lesions were histologically observed in high CO2 treatment. The results suggested that high CO2 negatively affected the growth and welfare of TGGG. Outputs of this study would offers a simple tool to evaluate the potential risk of elevated CO2 to an important commercial marine grouper.

Water temperature can influence the metabolic rate of ectothermal animal such as, fish. This study aims to investigate the gastric emptying time (GET) of malabar blood snapper (L. malabaricus) at different temperature (22, 26, 30, 34°C) fed with commercial diet pellet. The gastric emptying times at different temperatures were determined X-radiographically, using barium sulfate (BaSO4) as a contrast medium food marker. The food marker and X-radiography showed that initial voidance of fecal matter began 4-8 h after feeding at all temperature. The fastest GET (18 h) was obsereved at 30°C, whereas the longest (28 h) GET was seen at 22°C. GET was increased with increasing temperature up to 30°C whereas decreased at extreme (34°C) and stress temperature (22°C). The findings of this study suggest to culture L. malabaricus at 26-30°C with commercial diet pellet as this temperature ranges escalate the faster digestion process which may contribute faster growth rate of this commercially important fish species. Overall, the data obtained from this study may have important consequences for optimization of commercial production of malabar blood snapper.

Knowledge of fish gastric emptying time is a necessary component for understanding the fish feeding rates, energy budgets and commercial production of fishes in aquaculture. The hybrid grouper Epinephelus spp. is getting popular as a culture species in Malaysia for their faster growth rate compared to commonly cultured grouper species (giant grouper Epinephelus lanceolatus and tiger grouper Epinephelus fuscoguttatus). There are data suggests that elevated sea water temperature affects gastric emptying time (GET) of fishes. Hence, this study aims to study the GET of hybrid grouper at different temperature (22, 26, 30, 34°C) in laboratory condition with commercial diet pellet. The gastric emptying times (GETs) at different temperatures were determined X-radiographically, using barium sulfate (BaSO4) as a contrast medium food marker. The food marker and X-radiography showed that initial voidance of fecal matter began 4-6 h after feeding at all temperature. The fastest GET (13 h) was obsereved in the 30°C gro...