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Aim: This study explores the influence of temperature and diet on pepsin enzyme activity in TGGG hybrid groupers. Methodology: Two hundred TGGG groupers (body weight 200±10 g; total length 22.5±1 cm) were equally distributed in three rearing tanks (1500 l capacity). After three weeks of acclimatization, the groupers were kept in 40 tanks (5 fish per tank, 20 tanks with pelleted diet and 20 with shrimp diets) for 30 days. All treatments were replicated five times. Results: Pepsin activity increased with increased temperature, from 22°C (2.10 U mg protein−1) to 30°C (5.64 U mg protein−1) when the groupers were given either pellet or shrimp as diet. The shrimp-fed group showed significantly increased pepsin activity compared to pellet-fed fish. Interpretation: The pepsin enzyme activities in TGGG hybrid groupers were significantly influenced by temperature and diet, but the interaction of these two factors was insignificant. The results suggest that shrimp-diets given at 30°C water was ideal for rearing TGGG hybrid groupers. This suggests that combination proliferates enzymatic activity, which may lead to faster digestion and faster growth rates compared to other combinations.

With the ongoing climate change affecting the ocean, there is a need to understand and predict the future distributions of marine species in order to assess the sustainability of marine ecosystem. In this study, remotely-sensed satellite oceanographic data together with Indian mackerel (Rastrelliger kanagurta) fishery dataset were used to predict potential fishing grounds in the Exclusive Economic Zone (EEZ) of Peninsular Malaysia using boosted regression trees (BRT) model. The model was developed using three years (2008–2010) fish catch data and environmental variables of chlorophyll-a (chl-a), sea surface temperature (SST) and sea surface height (SSH). Result indicated that potential fishing grounds were closely associated with SSH, followed by SST and chl-a. The performance of the BRT model indicated acceptable fishing grounds prediction accuracy (AUC value of 0.749). Seasonal variability in fishing grounds was related to favorable environmental conditions of SSH (1.1–1.3 m), SST (29–32 °C) and chl-a (0.3–0.6 mg/m3). The projection of increases in SST due to climate change according to IPCC-AR5-RCPs was observed to influence the spatial and temporal distributions R. kanagurta. Increased temperature at 1.80 °C resulted in high potential catch areas for R. kanagurta in the EEZ. Meanwhile, elevated temperature at 2.60 °C and 3.30 °C showed decreased in potential catch areas for R. kanagurta in the EEZ. Most of the future fishing grounds area were projected to decline, and it was observed to shift outside the EEZ off South China Sea. Hence, by understanding these relationships, this analysis identifies where strategies can be adapted to face the ecological impacts under changing environmental conditions.

Increasing human-induced climate issues, such as water pollution, have triggered rapid physiochemical changes, especially in coastal regions. These changes have directly impacted aquatic animals that live near coastal areas, such as bivalves and crustaceans (e.g., clams, crabs), as well as those that live in the lower areas of the habitat (i.e., sediment). Heavy metal pollution (e.g., mercury) is one of the most concerning physiochemical changes in these areas. The effects of heavy metals on coastal environments and organisms can be substantial, in spite of restoration efforts. Thus, more studies are needed to analyze the current situation of the impacts of climate-change-related issues on heavy metal concentrations in coastal areas. In this paper, we provide a scientometrics analysis of the interactions between climate change and heavy metal concentrations in coastal regions around the world. Scientometrics is the quantitative analysis of the available literature, with a focus on research patterns, using continuous and systematic methods. Our results showed that there was a total of 7922 related studies from 1979 to 2021. Heavy metal contamination, ecological quality status and ocean acidification are among the most influential keywords in this field. We concluded that among climate change issues, heavy metals are becoming a popular topic within research associated with climate change.

Microplastic pollution in our environment, especially water bodies is an emerging threat to food security and human health. Inevitably, the outbreak of Covid-19 has necessitated the constant use of face masks made from polymers such as polypropylene, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester which eventually will disintegrate into microplastic particles. They can be broken down into microplastics by the weathering action of UV radiation from the sun, heat, or ocean wave-current and precipitate in natural environments. The global adoption of face masks as a preventive measure to curb the spread of Covid-19 has made the safe management of wastes from it cumbersome. Microplastics gain access into aquaculture facilities through water sources and food including planktons. The negative impacts of microplastics on aquaculture cannot be overemphasized. The impacts includes low growth rates of animals, hindered reproductive functions, neurotoxicity, low feeding habit, oxidative stress, reduced metabolic rate, and increased mortality rate among aquatic organisms. With these, there is every tendency of microplastic pollution to negatively impact fish production through aquaculture if the menace is not curbed. It is therefore recommended that biodegradable materials rather than plastics to be considered in the production of face mask while recycle of already produced ones should be encouraged to reduce waste.

This study explores the gastrointestinal evacuation time (GET) and gastrointestinal evacuation rate (GER) of the popular Sabah grouper (Epinephelus fuscoguttatus × E. lanceolatus) adults using two established methods (X-radiography and serial slaughter) and square root modeling using different temperatures: 28 °C, 30 °C, 32 °C, and 34 °C and different diets: pellet (ash: 11.4 ± 0.08; moisture: 29.0 ± 0.01; protein 37.5 ± 0.80; lipid 15.0 ± 0.13) and trash fish: Sardinella sp. (ash: 2.3 ± 0.15; moisture: 78.5 ± 0.33; protein 55.4 ± 0.62; lipid 7.3 ± 0.25) and the impact on growth indices. The results indicate that the GET shortened as temperature increased from 28 °C to 30 °C; however, it was prolonged when it surged to 32 °C and 34 °C. The groupers fed with trash fish at a temperature of 30 °C had the shortest GER (0.41 ± 0.10 g hr−1) whereas groupers fed with pellet at 34 °C had the longest GER (0.95 ± 0.02 g hr−1). Likewise, the highest SGR (16.25 ± 2.11% day−1) was observed at 30 °C for groupers fed with a trash fish diet. The condition (K) value was lowest at 34 °C for groupers fed with a pellet diet (1.01 ± 0.04) and highest at 30 °C for groupers fed with trash fish (1.45 ± 0.04). Our results suggest that temperature and diet influence growth indices and GE of adult Sabah groupers. Incorporation of this information will allow better management of this commercially important grouper species when reared in a controlled aquaculture environment.

Climate action was among one of the main targets for the United Nation Sustainable Development Goals (i.e. UN SDG: 13), which is to "take urgent action to combat climate change and its impacts". The United Nations Framework Convention on Climate Change (UNFCCC) is also concurred to improve climate change's mitigation and adaptation strategies along with the SDG's goals. Thermal tolerance has been proposed as one of the possible adaptation strategies for animals affected by anthropogenic effects and excess heat from climate change. However, no scientometrics analysis of thermal tolerance research has been conducted to date. As a result, the goal of this study was to gather information from the literature to determine the current state of thermal tolerance, development trends, and current research. Researchers will be able to better understand the trends and development of the thematic research area of thermal tolerance by using scientometric analysis to generate data on thermal tolerance. For frequency, co-occurrence, co-citation, clustering, and burst analysis, CiteSpace software was used. The scientometric review of thermal tolerance studies from 1970 to 2021 (5243 studies) reveals significant increases in the size of the literature, the frequency of citations, and the hotspots investigated. Susan Lindquist and the Journal of Thermal Biology are the most influential authors and journals, respectively. The most common clusters related to the thematic area of thermal tolerance are oxygen consumption and heat shock protein, with climate change and temperature being one of the most popular keywords. We concluded that, along with the thriving field and climate change issues, thermal tolerance is becoming one of the future research interests. In addition, knowing the current trends and developments of thermal tolerance in aquatic species is important for various stakeholders.

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.

This study was conducted to investigate the energy mobilization and ionoregulation pattern of tilapia living recirculating aquaculture system (RAS) and cage culture environments. Three different groups of tilapia were compared as tilapia cultured in RAS (Group I - RAS), tilapia cultured in open water cage (Group II - Cage) and tilapia transferred from cage to RAS (Group III - Compensation) as physiology compromising model. Results revealed that Group II tilapia mobilized glycogen as primarily energy for daily exercise activity and promoted growth, whilst tilapia from Group I and III mobilised lipid to support gonadogenesis and protein reserved for somatogensis. The gills and kidney NKA activities remained relative stable to maintain balance homeostasis with a electrolytes level. As a remark, this study revealed that tilapia re-strategized their energy mobilization pattern in accessing glycogen as easy energy to support exercise metabolism and mobilized lipid and protein for growth and gonadal development.

A specimen (125.5 mm in standard length) of bridled jawfish, Opistognathus nigromarginatus Rüppell, 1830 was collected from the Pulau Bidong, Terengganu, Malaysia using research trawler. Opistognathus nigromarginatus previously has been recorded from Southern Africa to the Persian Gulf, India, Thailand, and Vietnam. We document the first record of this species in Malaysia and the southernmost occurrence in the South China Sea and Western Pacific Ocean. Detailed morphometric and meristic data are presented along with brief diagnostic characters.

Length-weight relationship (LWR), condition factors, and trophic level of Zenarchopterus buffonis from the coastal waters of Malaysia were evaluated between November 2013 and March 2014. Three hundred individuals of Z. buffonis ranging between 8.7−16.0 cm total length and 3.67−22.19 g body weight were investigated in this study. The length-weight relationship demonstrated that the parameter b values at Sungai Likas, Tanjung Belungkor, Langkawi, Klang, and Matang were 3.3114, 3.0534, 2.5442, 2.2018, and 2.8998, respectively, which suggested positive and negative allometric growth patterns for this species. Specimens from Matang recorded the lowest mean condition factor, K (0.2292±0.0578) whereas Tanjung Belungkor displayed the highest value of 0.6556±0.0526. Matang was discovered to display the lowest relative condition factor (Kn) of 0.0330±0.2336, whereas Klang had the highest Kn value of 3.5097±0.4232. The trophic level for Z. buffonis was analyzed based on 84 specimens. Gut content analysis revealed that Z. buffonis consume primarily insects (57%), followed by plant materials (33%), and crustaceans (10%). The calculated TROPH values (1−3.2) signified that Z. buffonis has an omnivorous feeding habit. This study provides the pioneer description of LWR parameters, condition factors, and diet preferences for Z. buffonis, which would be beneficial for the sustainable fishery management in the coastal waters of Malaysia and neighboring provinces.

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

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

Carbon dioxide (CO2) concentrations at the ocean surface are in approximate equilibrium with the atmosphere. Consequently, the amount of CO2 dissolved in oceans increases with increasing atmospheric CO2 concentrations. Through ocean acidification, increase uptake of CO2 at the ocean surface lowers the ocean pH level. The availability of dissolved carbonate and bicarbonate primarily caused by CO2 uptake from the atmosphere also changes. Periodically or permanently elevated CO2 concentrations can become a general stress factor in aquatic environments. Excess CO2 can affect the surrounding ocean life, i.e., disturbing growth performance, reproduction, changes in skeletal and otolith development, and fish behavior. Studies on the effects of ocean acidification on fish species have recently received attention. This condition can lead to severe problems if atmospheric CO2 concentrations continue to rise. Therefore, management intervention and decisive action on excessive CO2 emission are necessary to overcome this situation. The information discussed in this review can be utilized as reference in understanding the effects of ocean acidification on marine ecosystem and associated fishes.

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 population genetic diversity and demographic history of the longtail tunaThunnus tonggolin Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals ofT. tonggolwere sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФSTsuggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989–1.000; ND5 = 0.848–0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019–0.025; ND5 = 0.0017–0.003), “star-like” haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations ofT. tonggolin Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.

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.

This study reports the discovery of the exclusive predation of sea turtle hatchlings by several juvenile blacktip reef sharks (Carcharhinus melanopterus) in Chagar Hutang bay on Redang Island, Malaysia, in the South China Sea. Three dead specimens of C. melanopterus were retrieved from ghost nets, and the entire digestive tracts of these sharks solely contained the partially digested bodies of sea turtle hatchlings, with no evidence of the remains of any other prey. Thus, juvenile C. melanopterus may opportunistically feed primarily on turtle hatchlings during times when hatchling abundance is high.

Marine biodiversity contains various unique life in the sea, from taxa to the ecosystem and provides valuable food sources and ecosystem services to humans and the environment. Climate change impacts towards marine biodiversity and ecosystem services have been done previously by various authors and countries. However, there is limited evidence on its impacts, especially in the form of scientometric study. The current study aimed to give an overview on the impact of climate change towards global marine biodiversity and ecosystem services. A scientometric methodology was implemented using the Web of Science (WoS) Core Collection database for the period from January 1970 to May 2021. Based on articles retrieved from the WoS, we found that the search query retrieved 2161 documents within the research area climate change, marine biodiversity and ecosystem services. A total of 60,051 times cited the total publication (i.e. 2161) with the h-index of 104 (i.e. 104 publications have received a minimum of 104 citations each) and an average of 27.79 citation per article (i.e. item). Research on this area has seen contributions from 3159 organisations worldwide with a huge number of authors involved, 10,319 in total.

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

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

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

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 population genetic diversity and demographic history of the longtail tuna Thunnus tonggol in Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals of T. tonggol were sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФST suggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989–1.000; ND5 = 0.848–0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019–0.025; ND5 = 0.0017–0.003), “star-like” haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations of T. tonggol in Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.