Aquaculture International最新文献

To address the crablet supply shortage for grow-out ponds, two experiments were conducted. The first aimed to identify the optimal combination of stocking density (SD) and culture duration (CD), while the second utilized this combination to determine the most effective ratio of artificial feed (F) to mussel meat (M) for nursery rearing of mangrove crab (Scylla serrata) megalopae into crablets. Each pond-based net cage (1 m² area) was provided with 1 unit each of shelter and feeding tray. The first experiment assessed four SDs (50, 100, 200, and 300 ind.m⁻²) at two CDs (3 and 4 weeks). Results showed that crablets at 50 ind.m⁻² had carapace width (CW) of 17.3 mm and final body weight (FBW) of 0.65 g after 4 weeks while the highest specific growth rate (SGR) of 19%/day was observed at 3 weeks. Although survival rates were higher (80–84%) at SD 50, 100, and 200 ind.m⁻², a higher final harvested number of crablets was achieved at higher SD 200–300 ind.m⁻² of 162 and 215 ind.m⁻², respectively. Using the SD 200 ind. m⁻², the second experiment evaluated 50F:50 M, 70F:30 M, 80F:20 M, and 100F alone on megalopa reared for 3 weeks. Results indicated that the 70F:30 M treatment obtained the highest SR of 69.9%, FBW of 0.28 g, CW of 12 mm, and SGR of 21.33%/day (p > 0.05). Our results indicate that a SD of 200–300 ind.m² and a feed ratio of 70F:30 M for 3 weeks are recommended for optimal growth and maximizing crablet production of Scylla serrata megalopae in nursery rearing.

This research aimed to assess the impact of integrating synbiotic (A-Pro Aqua®, SYN; 0.05 and 0.1%) and hydrolyzed yeast extract (Nutri Yeast-Aq®, HYE; 0.05 and 0.1%) as a factorial experiment 2 × 2 in a completel randomized design in the diet on growth performance, hemato-immunulogical responses, and digestive enzyme activities of Nile tilapia (Oreochromis niloticus) fry with intial weight 4 ± 0.2 g for 63 days. Three hundred fish were stocked in fifteen 120-L glass containers (20 fish per each unit) and fed with five diets containing control diet, 0.05% synbiotic + 0.1% yeast, 0.05% synbiotic + 0.05% yeast, 0.1% synbiotic + 0.1% yeast, and 0.1% synbiotic + 0.05% yeast. The findings indicated that elevated SYN and HYE levels significantly (P < 0.05) increased final weight, specific growth rate, volountary feed intake, survival rate, protein productive value, and protein efficiency ratio. Additionally, higher SYN and HYE levels resulted in a significant decrease in feed conversion ratio and hepatosomatic index (P < 0.05), while the activities of digestive enzymes such as protease, lipase, and amylase were considerably increased (P < 0.05). The synergistic application of SYN and HYE in the diet markedly enhanced alternative complement activity and triiodothyronine, immunoglubolin, and lysozyme concentrations in the plasma of test fish (P < 0.05). Moreover, the dietary supplementation SYN and HYE significantly elevated high-density lipoprotein concentation in the plasma of test fish while concurrently reducing low-density lipoprotein, very low-density lipoprotein, and triglyceride concentrations (P < 0.05). In summary, based on the growth parameters and hemato-immunological responses, dietary supplementation with 0.1% SYN in conjunction with 0.1% HYE was recommended.

Revealing the mechanism of aggregation behavior is of great importance in purposefully guiding and manipulating aggregation behavior. For the first time, the present study clarified that tube feet regulate aggregation behavior and investigated the underlying molecular mechanism in sea cucumber (Apostichopus japonicus Selenka), which belongs to the phylum Echinodermata, class Holothuroidea, order Aspidochirotida, family Stichopodidae, and genus Apostichopus. Residence time was significantly higher in the region with 20 sea cucumbers than in the region with 5 sea cucumbers, indicating that sea cucumbers themselves do play a role in the aggregation process. In addition, the proportion of aggregation in the area with tube feet was significantly higher than that of those without tube feet. This indicates that tube feet can attract sea cucumbers to aggregate. Further, the proportion of sea cucumbers aggregated in the region with crushed tube feet was significantly higher than that in the uncrushed tube feet region. This further verifies the role of tube feet in aggregation behavior of sea cucumbers. We found that the proportion of sea cucumbers aggregated in region with intact tube feet was significantly higher than in region where tube feet were removed. This further suggests that tube feet, rather than other parts, attract sea cucumbers to aggregate. Interestingly, the present study found that sea cucumbers significantly aggregated on the rough stone with 20 sea cucumbers attached than on the acrylic plate with 20 sea cucumbers attached. Consistently, the aggregation behavior significantly enhanced after the injection of potassium ion solution. This suggests that potassium ions probably affect the aggregation behavior of sea cucumbers. We also found that the proportion of aggregation was significantly lower in sea cucumbers injected with HC-030031 (25 μL) than those injected with DMSO (25 μL), while the aggregation proportion of sea cucumbers injected with 5-HT (25 μL) was significantly higher than that injected with normal saline (25 μL). These results suggest that the aggregation behavior may be manipulated by adhesion proteins released by the tube feet, and are probably achieved through TRPA1 pathway perception and 5-HT conduction.

The Portuguese oyster, Crassostrea angulata, is an important aquaculture bivalve species in Asia. This study was carried out to estimate genetic parameters at 240 days, 300 days and 365 days for survival rate and whole weight over six generations of selection. The phenotypic measurements for whole weight and survival rate at 240, 300 and 360 days were collected from the fourth to sixth generations. A linear mixed model was used to estimate heritability and genetic correlations at 240, 300 and 365 days after fertilization for whole weight, and a generalized linear mixed model was used to estimate heritability and genetic correlations at 240, 300 and 365 days for survival rate. Heritability estimates for whole weight were moderate at three studied times, ranging from 0.10 to 0.18. Heritability estimates for survival (h² = 0.11–0.12) whole weight trait and estimates of genetic correlations between survival and whole weight at the three studied ages were moderate to high (0.55–0.77), suggesting that selection to improve one trait at specific, for example, 240 days, 300 days or 365 days, can result in favourable changes in another trait.

A 60-day feeding trial was carried out to assess the effects of substituting fish meal with graded levels of algae meal (AM) (Arthrospira platensis) alone or supplemented with fish protein hydrolysate (FPH) on growth performance and nutrient utilization of striped murrel (Channa striata). Five isonitrogenous (44% crude protein), isolipidic (11% crude lipid), and isoenergetic (18 MJ/kg gross energy) diets viz. Control (consists of 35% fish meal), 25% algae meal (25AM), 50% algae meal (50AM), 25% algae meal and 1% FPH (25AM + FPH), and 50% algae meal and 1% FPH (50AM + FPH). A total of four hundred and fifty (450) juveniles of Channa striata (average weight: 9.85 ± 0.30 g) were randomly stocked in 15 experimental cages (1 m × 1 m × 1.5 m) at a stocking density of 30 fish/cage in triplicates. The juvenile striped murrel were fed three times a day until apparent satiation (08:00, 13:00, and 18:00 h). Among all the dietary groups, fish fed the 25AM + FPH diet showed significantly higher (p < 0.05) growth performance and nutrient utilization than fish fed the other diets. The inclusion of AM alone or in combination with FPH diets did not affect the whole-body proximate composition and hemato-biochemical profile of striped murrel (p > 0.05). Significantly (p < 0.05) higher digestive enzyme and antioxidant enzyme activities, intestinal villi length and width, and IGF-1 gene expression were found in fish fed the 25AM + FPH diet which was not different from the control diet. In conclusion, algae meal supplemented with FPH (25AM + FPH) can replace dietary fish meal up to 25% without affecting growth, nutrient utilization, whole-body composition, digestive enzyme activities, intestinal villi length and width, hemato-biochemical responses, and IGF-1 expression in striped murrel. However, replacing more than 25% of fish meal with AM alone or combination of AM and FPH adversely affected the growth performance and nutrient utilization in striped murrel (C. striata). Therefore, this research suggests the potential of combining AM and FPH as a sustainable alternative to fishmeal. This combination with an inclusion level of 25% proved beneficial for C. striata, demonstrating its viability for future feed formulations.

Sex-specific molecular markers are effective tools for genetic sex identification and sex control breeding in aquaculture. Bullfrog (Aquarara catesbeiana) is a kind of aquatic animal that possesses sexual dimorphism in the prospects of growth traits like body size and age of sexual maturity. However, it is difficult to perform the process of sex identification because of the undeveloped secondary sexual characteristics at the juvenile stage of A. catesbeiana. Here, we constructed two different strategies for the detection of sex-specific markers from four mixed-pool samples using whole genome sequencing technology (WGS). Subsequently, four male-specific markers were identified and validated in another eight male frogs and eight female frogs. Moreover, the results revalidated the male heterogametic system in A. catesbeiana. These may be the first four rapid, accurate, and effective male-specific molecular markers used for genetic sex identification in bullfrogs. The results could fill the gap in research on sex-specific markers of bullfrogs and provide convenience for further research on amphibian sex determination and mono-sex breeding work. Furthermore, two detection strategies could possess the applied value in the identification of sex-specific markers in production.

This study investigated the effects of chronic ammonia exposure on the growth parameters, intestinal histology, and digestive enzyme activity of aquatic fish. Blunt snout bream, Megalobrama amblycephala juveniles, with 6.55 ± 0.24 g were exposed to 0 (G1), 6.82 (G2), and 13.64 mg/L (G3) NH₄Cl (ammonium chloride) for 56 days. Then, the intestinal enzyme activity and histological characteristics of blunt snout bream were analyzed using modern biological techniques. The results showed that chronic ammonia exposure significantly decreased the final body weight and specific growth rate of blunt snout bream (p < 0.05). The intestinal protease, lipase, amylase, CK, AKP, and γ-GT activities of blunt snout bream after chronic ammonia exposure significantly decreased (p < 0.05). Meanwhile, the intestinal muscularis thickness and microvillus density of fish decreased as the increased ammonia concentration. The intestinal microvillus length of blunt snout bream after chronic ammonia exposure significantly reduced compared to the control group (p < 0.05). Furthermore, chronic ammonia exposure caused a significant down-regulated expression of Occludin, ZO-1, Claudin-3c, and Claudin-7 mRNA in the intestine (p < 0.05) but up-regulated the levels of NF-κB, TNF-α, IL-1β, and IL-6 mRNA (p < 0.05). Overall, chronic ammonia exposure inhibited the growth and compromised the intestinal structure of fish.

This study aimed to determine the potential efficacy of dietary prebiotics, probiotics, and synbiotic on growth performance, total hemocyte count (THC), hepatopancreas histology, and gut microbiota composition of brown shrimp (Penaeus aztecus) under biofloc technology (BFT) conditions for 84 days. Seven feed additive groups were formed as C: control group with no feed additive, P: probiotic mixture (1 mL, 1 × 10⁹ CFU/100 g feed, Lactobacillus plantarum, L. acidophilus, L. salivarius, and Bacillus subtilis), A: 0.2 g Arthrospira/100 g feed, S: P + A, ES1: P + A + 0.1 g MOS/100 g feed, ES2: P + A + 0.2 g MOS/100 g feed, ES3: P + A + 0.3 g MOS/100 g feed. At the end of the trial, P, A, and S showed an intermediate effect on final body weight (FBW) compared to the control group, while FBW significantly increased in the ES1, ES2, and ES3 groups (P < 0.05). Gut microbiota diversity revealed a predominance of Proteobacteria phylum and a decrease in Bacillota phylum in dietary prebiotic, probiotic, and synbiotic treatments. The number of B cells increased in the hepatopancreas of brown shrimp fed diets containing feed additives, indicating a significant effect on hepatopancreatic tubules. THC levels of the shrimps in the experimental groups increased, and the highest values were reached in shrimps fed with synbiotic diets (P < 0.05). In conclusion, it can be concluded that enriched synbiotic diets supplemented with probiotic mixture, Arthrospira, and mannan oligosaccharide can promote healthy growth for brown shrimp under BFT conditions.

The present study evaluated the ability of fish waste hydrolysate (FWH) to improve the growth and health of Penaeus monodon in outdoor tank systems and earthen ponds. The FWH is a value-added product prepared from marine fish trimmings/wastes from fish markets and processing units. A 60-day trial was conducted in an outdoor tank system with 7 doses of FWH (0, 5, 10, 20, 40, 80, and 160 ppm). The results indicated that P. monodon grown in treatments supplemented with FWH at 20 ppm and above had significantly improved specific growth rate (SGR), weight gain (WG), and feed conversion ratio (FCR) than control and lower doses of FWH (p < 0.05). Survival, average daily gain (ADG), and % weight gain followed similar trends. All FWH-treated groups exhibited significantly higher floc densities (p < 0.05), with enhanced phytoplankton and zooplankton abundance compared to the control. Haematological analysis indicated improved health status in FWH-treated shrimp. Subsequently, a field trial of P. monodon was conducted in farmer’s ponds in Kannur district, Kerala, India. The treatment pond was supplemented with 40 ppm FWH and the control pond was without FWH supplementation. A significant difference (p < 0.05) was observed in the growth (16% higher growth) of the animals in the FWH-supplemented pond compared to that in the control. The improved growth might be due to the enhanced natural food abundance of phytoplankton and zooplankton in the pond supplemented with FWH. This study highlights FWH as a sustainable approach to enhance P. monodon growth while converting fish waste into valuable protein.

Graphical Abstract

Blue crab aquaculture faces challenges in optimizing feed formulations that balance nutritional requirements with sustainability. This study evaluated three innovative feed formulations incorporating unique ingredient combinations: a specialized high-protein formulation using novel protein hydrolysates (D1), a marine-based diet enriched with bioactive compounds from sustainable sources (D2), and an advanced plant-based formulation with enhanced digestibility through fermentation (D3). Growth performance, survival, energy conversion efficiency, molting frequency, and meat quality were assessed over 16 weeks. The marine-based diet (D2) achieved superior results with 92% weight gain and 95% survival rate, significantly outperforming the commercial control. This research demonstrates the potential of novel ingredient combinations and processing techniques in enhancing blue crab aquaculture productivity while addressing sustainability concerns.