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The ongoing climate change is resulting in elevating temperatures and reduced pH levels in the marine environment. This work reports on the interactive effects of these two factors on growth and physiological responses of Pacific whiteleg shrimps (Litopenaeus vannamei), with a very important commercial shrimp specie. The study examines the interactive effects of temperature (28 versus34°C) and pH (6 versus 8) were examined at four combinations: (28°C and pH 8 (N28); 34°C and pH 8 (N34); 28°C and pH 6 (A28); and 34°C and pH 6 (A34), over a 30 days period. A combination of a high temperature and low pH (i.e., A34) was found to impose a high metabolic burden on the shrimp, resulting in an increased food intake and elevated osmorespiration responses relative to control, but no improvement in growth. The A34 stress combination increased ammonia excretion 2-fold relative to control, and increased a 40 % rise in metabolic oxygen uptake. Under A34 stress, glycogen and lipid reserves in both muscle and hepatopancreas were mobilized to support basal metabolic needs, resulting in growth suppression. The combined thermal-pH stress A34 did not affect the calcium and magnesium content of muscle and shell, which are essential minerals for exoskeleton and structural development. Although the shrimp can survive under high temperature-low pH stress conditions, their growth rate was compromised.

Current water warming and freshwater acidification undoubtedly affect the life of aquatic animals especially ammonotelic teleost by altering their physiological responses. The effect of temperature (28 °C vs 32 °C) and pH (7 vs. 5) on the metabolic compromising strategies of Hoven's carp (Leptobarbus hoevenii) was investigated in this study. Fishes were conditioned to (i) 28 °C + pH 7 (N28°C); (ii) 32 °C + pH 7 (N32°C); (iii) 28 °C + pH 5 (L28°C) and (iv) 32 °C + pH 5 (L32°C) for 20 days followed by osmorespiration assay. Results showed that feeding performance of Hoven's carp was significantly depressed when exposed to low pH conditions (L28°C and L32°C). However, by exposed Hoven's carp to L32°C induced high metabolic oxygen intake and ammonia excretion to about 2x-folds higher compared to the control group. As for energy mobilization, Hoven's carp mobilized liver and muscle protein under L28°C condition. Whereas under high temperature in both pH, Hoven's carp had the tendency to reserve energy in both of liver and muscle. The findings of this study revealed that Hoven's carp is sensitive to lower water pH and high temperature, thereby they remodeled their physiological needs to cope with the environmental changes condition.

The growth pattern, diet and reproductive biology of the clownfish Amphiprion ocellaris collected from waters of Pulau Tioman were investigated. The length-weight relationship showed an isometric growth pattern (b = 3) in A. ocellaris. The stomach contents mainly consisted of zooplankton and algae, which showed that the fish is omnivorous and was confirmed by trophic level analysis (2.98 ± 0.29). Fecundity of A. ocellaris ranged from 23-1518 with mean egg count of 582 ± 478, and has positive relationships with body length, body weight, eviscerated weight and ovary weight. The gonads were also described and examined histologically. The ovaries showed 4 stages of maturity, displaying different colours for each stage. The different developments of oocytes were also found in each stage of maturity. The males and non-breeders comprised of both testicular and ovarian tissues. In the males, the testicular tissues were more prominent in the ovotestes, whereas in non-breeders the primary oocytes were more prominent. Absence of testicular tissue in ovaries of females showed that the fish is a protandrous hermaphrodite and sex change may not be reversible. Similar observations have been reported in A. ocellaris of other countries and other Amphiprion species indicating that Amphiprion species show consistency in their reproduction strategy throughout their range. Keywords: Reproductive biology, Growth pattern, Stomach content, Amphiprion ocellaris, Protandrous hermaphrodite

An integrated experiment was performed on juvenile Malabar blood snapper (Lutjanus malabaricus) to investigate the effect of temperature and diet in their pepsin activities in relation with digestive somatic index (IDS) and relative gut length (RGL). One hundred twenty L. malabaricus juvenile (13–15 cm) were equally distributed among four exposed temperature treatments (22, 26, 30 and 34 °C) representing their seasonal range and to account for end of century predicted temperatures, and two diets as commercial pellet and natural shrimp. After 7 days of acclimation period fish were reared for 30 days in twenty four 400 l glass aquaria at a stocking density of 5 fish tank−1. All treatments were three replications. The result showed that, IDS and RGL gradually decreased with increasing temperature up to 30 °C and again increase at 34 °C. And the values were also higher in pellet feeding fish than shrimp feeding fish at all the temperatures. Alternatively, in pepsin activity, an increased activity was seen between 26 °C to 30 °C and this activity was significantly higher than the 22 °C and 34 °C (P

The influences of live and formulated feeds on growth performances, muscle fibers morphometry and muscle growth-related gene expression of Malaysian mahseer, Tor tambroides larvae were evaluated in indoor nursery rearing system. Quadruplicate groups of T. tambroides larvae (0.07 ± 0.01 g, mean ± SE) were stocked in sixteen aquaria (60 × 30 × 30 cm), randomly arranged in four dietary treatments viz. larvae fed artemia (LA), moina (LM), daphnia (LD) and formulated feed (FF) with stocking density of 34 larvae per aquarium. The larvae were fed to visually near satiation in two equal feedings per day, seven days per week for 75 days. The growth-related parameters (mean weight gain and specific growth rate) were significantly highest in treatment FF, followed by treatment LA and the lowest in treatment LD or LM. Histological observation and muscle morphometric analysis revealed that mosaic hyperplasia was observed after 50 days of the feeding trial. Hypertrophic (diameter class 50 = 40 > d ≤ 50 μm and class 60 = d > 50 μm), but not hyperplastic (diameter class ≤10 μm), muscle fibers frequencies were significantly highest in larvae fed FF compared to those fed live feeds. The entire open reading frame cDNA sequences of two important growth-related genes, myogenin and MyoD, were successfully amplified and cloned from T. tambroides larvae. The nucleotide sequences alignment using CLUSTAL W in BioEdit program of both MyoD and myogenin genes showed the sign of existence of isoforms and highly conserved with other cyprinid fishes. Real-time PCR data demonstrated that myogenin and MyoD gene expressions were significantly upregulated in larvae fed FF. The results of the present experiment concluded that the nursery rearing of T. tambroides larvae with formulated feed showed augmented muscle growth and upregulated growth-related gene expression than feeding live feeds.

Macrobrachium rosenbergii is one of the shellfish species with high aquaculture value due to its increasing market demand. However, the comparatively low production volume compared to demand coupled with the rapid decline of the natural environment, consequently, drives the potential depletion of the wild population. The decrease in water pH related to anthropogenic pollution is one of the most critical factors affecting the early life performances of M. rosenbergii. Therefore, this study was designed to examine the effect of low water pH on feeding, growth and development of M. rosenbergii early life stages. Experimental water pH was set as neutral (7.7 ± 0.4); mild-acidic (6.4 ± 0.5) and acidic (5.4 ± 0.2) with triplication at a stocking density of 2 larvae/L for 30 days. As expected, M. rosenbergii larvae were highly sensitive to acidic pH with no larvae survived beyond 48 h of exposure. Feeding, survival and growth of larvae were adversely affected by mild-acidic pH exposure as compared to neutral pH. Larvae exposed to mild-acidic water pH experienced a prolonged larval period and only metamorphosed to the post-larval stage at day-30. Whilst under neutral water pH, larval that metamorphosed to post-larval was first observed on day-23. The negative impact of decreased pH, even in mild-acidic pH exposure, on the feeding, survival, growth and development of M. rosenbergii larvae highlights the urgency of periodic pH monitoring during M. rosenbergii larviculture.

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.

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