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Intensive research on the effectiveness of chemoattractants has been widely explored to improve the feed qualities in expanding crustacean farming. Taste preferences in slipper lobster remained unknown despite their significant contribution to the lobster fisheries. Chemoattractants allow better performance in aquaculture species by increasing food attractiveness and palatability. Amino acids (AA) have been leading in previous research on crustacean feeding behavior. Given that slipper lobster possesses chemoreceptors to detect and orient towards food, this study investigated an approach to identify the AA with the most potent chemoattractant in eliciting a response from slipper lobster. Behavioral assays were performed to evaluate the responses of slipper lobster Thenus orientalis (carapace length, 52.34 ± 1.52 mm) on 15 crystalline AA and three derivatives of AA (DAA) at three concentrations between 10-1 and 10-3 3 M as test substances (TS). Meretrix sp. extract was used as a positive control and clean filtered seawater as a negative control. The behavioral responses of 14 T. orientalis were evaluated based on their antennular flicking rate, third maxillipeds activity, and substrate probing by the pereiopods. T. orientalis responded to the solutions of single AA down to a concentration of 10-3 M, excluding histidine and serine. The behavioral activity displayed by T. orientalis increased with the TS concentrations. L-glutamic acid monosodium salt monohydrate, betaine, and glycine solutions elicited the most behavioral responses, whereas histidine exhibited the lowest behavioral responses. Conclusively, L-glutamic acid monosodium salt monohydrate, betaine, and glycine can be potential chemoattractants for T. orientalis. [ABSTRACT FROM AUTHOR]

Context: Swimming crab is a vital fishery resource and a valuable source of income in the southern East China Sea, but it lacks management strategies, especially when using different fishing gear. Aims: This study aimed to determine the effects of spatial–temporal conditions and vessel capacity on swimming crabs by using different fishing-gear types in the Taiwan Strait (TS). Methods: We used generalised linear mixed models (GLMMs) to investigate data from Taiwanese vessels (2011–2019) on how spatial–temporal conditions and vessel capacity affected the catch of swimming crabs when using trawls, gill-nets and traps. Key results: The results showed that the traps (>80.0%) caught more swimming crabs in the TS than did the gill-nets (6.6%) and trawls (8.0%). Additionally, the GLMM analysis showed that Charybdis feriatus , Portunus pelagicus and Portunus sanguinolentus catches by traps and trawls were significantly affected by different fishing locations, climate events, work hours and vessel sizes. However, for gill-nets, spatial–temporal conditions and vessel capacity did not affect the catch of C. feriatus. Conclusions: Monitoring fishing efforts and environmental factors is vital to understanding their impacts on marine ecosystems. Implications: These findings enable future sustainable crab fishing through harvesting strategy planning, ecosystem management and spatial–temporal governance. The catch performance of fishing gear depends on species' behaviour, habitat, fishing grounds, fishing regulations and oceanographic conditions. Besides, to optimise the catch, experienced fishermen mostly use the right gear at the right time and place. Therefore, the fact that baited traps more efficiently target swimming crabs than do other gear types may be due to two critical factors, namely, the habitat of the crabs in the benthic area and the chemoreceptive sensory behaviour of crabs in detecting the bait. [ABSTRACT FROM AUTHOR]

In this study, climbing perch larvae were administrated with different diet treatments: Artemia nauplii enriched with 108 CFU mL−1L. lactis (LA); nauplii enriched with 0.5 g L−1 sodium alginate (SA); nauplii enriched with 0.5 g L−1 sodium alginate containing 108 CFU mL−1L. lactis (LSA); and non-enriched nauplii as the control (A). Throughout the 14-day observation period, fish larvae survival rate significantly increased to 50% (P <.05) in the group fed with LSA, followed by LA (41.7%) and SA (31.7%) while only 20% survival rate was observed in the control. The highest lysozyme activity was recorded in LSA (13.89 units mg−1 protein), followed by LA, SA, and A. Fish larvae treated with LA also showed a significant increase in lipase (P =.024) and amylase activities (P=.003) compared to those treated with LSA and SA. Our study indicated that L. lactis and alginate or the combination of both treatments (LSA) could improve the survival rate by upregulating their innate immune response. [ABSTRACT FROM AUTHOR]

The jewel cichlid Hemichromis bimaculatus is a popular freshwater ornamental fish with high market demand. However, it is aggressive and difficult to be maintained in captivity. Background colours are known to influence fish aggression, but there is still no such information available on H. bimaculatus. This study was conducted to examine the influence of 6 background colours (black, white, blue, yellow, green or red) on the aggression (chasing frequency), survival, weight gain and feed intake of the H. bimaculatus, through a 60‐day culture trial. At the end of this trial, since the total feed intake and fish weight gain (except black) were similar among all treatments, the green was the most recommended background colour for the H. bimaculatus culture as it has the highest fish survival, followed by the white and yellow. Low fish survival was found under the black, red and blue; hence, these background colours were not recommended. In this study, we suspected that different background colours may induce different aggressiveness degree in the H. bimaculatus, and biting may have occurred to cause low fish survival. Also, the blue was speculated to be a stressful background colour to the H. bimaculatus. Nevertheless, further study is necessary to elucidate these hypotheses. [ABSTRACT FROM AUTHOR]

The aquaculture of decapod crustaceans is expanding continuously to supply protein source for human consumption. Therefore, intensive research is necessary to improve the quality of the feeds in decapod crustacean farming. Decapod crustaceans are slow feeders, and dietary inclusion of plant proteins reduces their intakes on the feeds. Dietary supplementation of chemoattractants (CA) (to reduce food searching duration) and feeding stimulants (FS) (to stimulate ingestion) is therefore necessary to solve these problems respectively. Amino acids are commonly used as the CA and FS in aquaculture, and the feeding response of aquatic animals to amino acids is species‐specific. As the chemosensory systems of decapod crustaceans are complicated, and their feeding responses are different from fish, it is essential to understand which amino acids can function as the CA, FS or both to the targeted farmed species. This review provides an overview on the acceptance of some commercially farmed decapod crustaceans to amino acids. Topics related to the efficiency of amino acids being a CA and FS were discussed, and recommendations on how to present amino acids as a CA and FS efficiently in decapod crustacean farming were also made. [ABSTRACT FROM AUTHOR]

Rapid development has been associated with mercury pollution in the aquatic environment, leading to mercury toxicity in fish and other aquatic organisms. Histopathological abnormalities such as hyperplasia, inflammation, and necrosis have been observed in various fish tissues as a result of mercury contamination based on organic mercury (methylmercury) and inorganic mercury (mercuric chloride) exposure via dietary or water exposure, respectively, with different duration doses of mercury. Knowing that tissue changes occurred at an important part of each organ that played various critical roles in the normal physiological actions of fish, it is critical to understand how fish respond to mercury contamination and how this heavy metal element affects their general well-being. This review paper focuses on major tissue histopathology changes in response to mercury toxicity and their potential use as a mercury contamination indicator in fish. [ABSTRACT FROM AUTHOR]