Cypermethrin exposure: Implications for growth, phenotypic attributes, and biochemical responses in monosex tilapia (Oreochromis niloticus).

The present study was conducted to evaluate the effects of exposure to sublethal concentrations of cypermethrin on growth, phenotypic traits, and metabolic and antioxidant enzymes activities of monosex tilapia (Oreochromis niloticus). The median lethal concentration (LC50) of cypermethrin was initially ascertained to be 0.04 ppm after 12 h of exposure to three concentrations (0.04, 0.20, and 1.0 ppm) via the Probit analysis method. The sublethal exposures were obtained for 3 months at 0.0016, 0.008, and 0.04 ppm of cypermethrin. The growth performance, phenotypic traits, and enzymatic activity were analyzed. The research findings revealed a notable impact of cypermethrin on the growth performance of monosex tilapia, with a significant (p < 0.05) decrease in weight observed as the concentration increased. The experiment documented a significant change (p < 0.05) in the phenotypic traits of standard length, total length, tail length, trunk length, eye diameter, body area, and color patterns, but not dressing percentage. Furthermore, it was observed that the activities of amylase and protease in both the intestine and muscle decreased significantly (p < 0.05) with increasing concentrations of cypermethrin, except for amylase in the muscle, where no significant change was noted (p > 0.05). The results also demonstrated significant reductions (p < 0.05) in the activity of metabolic enzymes, specifically superoxide dismutase and catalase, following exposure to sublethal levels of cypermethrin. The study suggested that sublethal exposure of pyrethroid alters the growth, phenotypic traits, metabolic enzymes activities, and immunity of monosex tilapia.

Unveiling the biofloc culture potential: Harnessing immune functions for resilience of shrimp and resistance against AHPND -causing Vibrio parahaemolyticus infection.

In shrimp aquaculture, disease mitigation may be accomplished by reducing the virulence of the pathogen or by boosting the shrimp's immunity. Biofloc technology is an innovative system that improves the health and resistance of shrimp to microbial infections while providing a viable option for maintaining the quality of culture water through efficient nutrient recycling. This review aimed at demonstrating the efficacy of the biofloc system in boosting the immune responses and protective processes of shrimp against Vibrio parahaemolyticus infection, which is known to cause Acute Hepatopancreatic Necrosis Disease (AHPND). Numerous studies have revealed that the biofloc system promotes the immunological capability of shrimp by raising multiple immune -related genes e.g. prophenoloxidase, serine proteinase gene, ras-related nuclear gene and penaeidinexpression and cellular and humoral responses such as hyperaemia, prophenoloxidase activity, superoxide dismutase activity, phagocytic activity; the protection and survival of shrimp when faced with a challenge from the V. parahaemolyticus strain have been enhanced. Furthermore, the use of the biofloc system improves water quality parameters and potentially bolstering their immune and overall health to effectively resist diseases; hence, promotes the growth of shrimp. The present review suggests that biofloc can serve as an effective therapy for both preventing and supporting the management of probable AHPND infection in shrimp culture. This approach exhibits potential for the progress of sustainable shrimp farming, higher productivity, and improved shrimp health.

Estimating peak breeding season, size at first maturity and variation in fecundity and egg-size at different sizes of Hilsa (Tenualosa ilisha).

Hilsa shad, Tenualosa ilisha, has recently gained momentum due to its taste, nutrition and demand. Imposing ban at peak breeding and setting up a minimum capture size are two of the most effective tools for conservation and management of any fish species. Although, Bangladesh government has been imposing ban on a particular time and set the minimum legal size, there is still contradictory information on these two issues. That is why, a study was carried out to determine peak season of breeding and first maturity of Hilsa collected across the natural habitats in Bangladesh. Variation in fecundity and egg-size at different sizes were also investigated. Peak breeding season was identified observing gonadosomatic index of female Hilsa all the year round. First maturity was estimated with Probit analysis. Based on the gonadosomatic index of gravid females, peak breeding season was identified as late October to early November in this study. However, another minor peak was found in February-March. The highest GSI value (12.1) was observed in October-November, which indicates the peak time of spawning. The size at maturity (M50) of female Hilsa was estimated as 31 cm total length. A significant variation was observed in egg sizes between the left and right lobes of the fish (t (24) = 2.42, p = 0.02), and between the parts of the same lobe (p = 0.03). However, fish length and weight had no effect on egg size(for egg-size vs. fish length, r = -0.009, p = 0.966; and for egg size vs. body weight, r = 0.132 and p = 0.530). The average egg count from left lobe and right lobe were recorded as 0.375 ± 0.16 million, 0.371 ± 0.17 million. Total fecundity was counted as 0.745 ± 0.33 million. A significant positive correlation was noticed between length, weight, and total fecundity (r = 0.7 for total fecundity vs. body weight; r = 0.6 for of total fecundity vs. length). No significant variation was observed in fecundity between the left and right lobe (p = 0.6) and among three parts of a lobe (p = 0.3). The size of eggs varied between two lobes and among different parts of a lobe. The eggs from middle part were bigger in size than the other parts. The findings of our study will help conserve and manage the natural population of Hilsa (T. ilisha) in Bangladesh and contribute to the wider scientific community.

Comparative growth and morphometric assessment between cultures of wild and hatchery-produced mud crabs.

This paper reports the comparative growth, nutritional performance, and morphometric variation between wild and hatchery-reared juvenile mud crabs (Scylla olivacea) in earthen ponds. The crabs were fed daily with boiled tilapia paste at a feeding rate of 5-8% body weight for the first two weeks, followed by feeding with chopped eviscerated tilapia until termination of the experiment. Selected phenotypic trains, including carapace width (CW), carapace length (CL) and abdominal width (AW), were measured weekly. The protein content of the muscle (21.13%), gill (13.51%) and egg (43.28%) were significantly higher in the hatchery-sourced compared to wild female crabs (muscle = 19.15%; gill = 10.09%; egg = 38.15%). Likewise, the hatchery sourced crabs exhibited higher lipid content in the muscle (2.45-2.51%) and eggs (7.51%) compared to the wild counterparts (muscle = 1.45-1.47%; egg = 6.15%). These findings suggested a superior nutritional quality of the hatchery-reared compared to the wild-sourced crabs. Although some selected phenotypic traits did not vary among the wild and hatchery-reared crabs (p < 0.05), their survival rates varied significantly depending on the stocking density (p < 0.05). Overall, the findings suggest that the growth characteristics of the hatchery produced and wild-sourced crab were similar, which will help to remove the misconception among the crab farmers about the hatchery seeds and promote diversification of the crab production system for long-term sustainability.

Identifying peak breeding season and estimating size at first maturity of mud crab (Scylla olivacea) from a coastal region of Bangladesh.

Recently mud crab (Scylla olivacea) has emerged as a potential export commodity. Its farming is increasing rapidly in Bangladesh because of its lucrative price and high demand in international market. However, the farming or fattening of mud crab is totally dependent on capture of wild crablets. A huge quantity of mud crabs is being caught indiscriminately from nature and thus putting intense pressure on its wild stock, which is a major concern of conservation. Imposing ban at peak breeding season and setting a legal capture size are considered effective management tools for safe migration and spawning of berried females. There is contradictory information on breeding season of mud crab in Bangladesh. Thus, it is crucial to identify the peak breeding season of it and to formulate conservation policies to protect the berried crabs. Live crabs were collected year-round from the river adjacent to southwest part of Sundarbans. Although mud crab breeds throughout the year, March-April was identified as the peak breeding season of it. The second peak was observed in August-September. The highest abundance of crablets (1-2 months age) was recorded in May-June, and the lowest in January-February. Immature crablets were found all through the year that proves that mud crab is a continuous breeder. The highest amount of GSI value (11.6) was observed in February-March, which indicates that the breeding is very near. The size at first maturity (M50) was estimated as 95.5 mm CW which lied at size class 91-100 mm (CW). The findings from the study will assist in fixing up the banning time and thus protecting the mother crabs; and will assist in formulating police to conserve and protect juvenile crabs in the sense that the minimum legal capture size of crabs will allow the adults to mate and spawn at least once before their capture.

Rapid identification of enterovirulent Escherichia coli strains using polymerase chain reaction from shrimp farms.

Although, Escherichia coli is widely distributed in the environment, only a small percentage is pathogenic to humans. The most commonly encountered are those belonging to the Enterotoxigenic (ETEC), Enteroinvasive (EIEC), Enterohaemorrhagic (EHEC) and Enteropathogenic (EPEC) subtypes. Aquaculture premises specially shrimp farm in tropical and subtropical countries largely susceptive to different types of E. coli strains. With the PCR system, an attempt was taken to identify the virulent E. coli in a rapid basis from water, sediment and live shrimp from different shrimp farms established in the shrimp production areas of southwest part of Bangladesh. The target genes chosen for this investigation included the PhoA, a housekeeping gene in all E. coli and thereafter the virulent genes LT1, LT1 and ST1 of ETEC, the VT of EHEC and EAE of EPEC, which were amplified with the primers designed for their specific genes. The restriction enzyme conformation and the gel electrophoresis bands showed the presence of E. coli, among which ETEC and EPEC groups were present in the environmental and biological samples of shrimp farms, brings up into the human health concern. The sanitation conditions amid farm were also investigated to find the link of pathogenic E. coli, which came into the result of less infection if the farm maintains improved sanitation. This study has clearly urged the exigency of periodical quick check of virulent E. coli with the versatile PCR system from brood management to post-harvest handling of shrimp.