Aquaculture Research最新文献

Limited information exists on the dietary requirements of the African bony-tongue (Heterotis niloticus) fry as well as the suitable age to wean fry from live prey to formulated diets. These have been the major challenges to the commercial culture of the species. This study assessed the optimal weaning age of fry as well as the effect of varying phospholipid (PL) content and long chain polyunsaturated fatty acids (LC-PUFAs) on survival, performance, and digestive enzyme activity of H. niloticus fry. The two weaning diets used were formulated to be isonitrogenous, isolipidic, and isoenergetic (49% CP, 20% CL, and 22.7 MJ/kg). The diets differed only in the content of PLs and LC-PUFAs; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Soy lecithin (PLs) and Algatrium DHA70 (a glyceride product high in DHA and EPA) were included at two levels. The diets were, respectively, labeled low phospholipid (LPP) (formulated to contain: 3.16% PLs, LC PUFAs: 0.66% DHA 0.10% EPA) and high phospholipid (HPP) (formulated to contain: 12.96% PLs, LC PUFAs: 3.04% DHA, 0.75% EPA). African bony-tongue fry were fed Artemia nauplii until 15, 25, 35, 45, 65, or 85 days after hatching (DAH), respectively, then cofed with Artemia and one of the two weaning diets for an additional 7 days after which Artemia feeding was completely withdrawn. Hereafter, the fry were maintained solely on the experimental diets for 10 days. A control group was kept on Artemia nauplii throughout the experiment. The results showed that the survival rate of fish on the LPP and HPP diets increased significantly (p  < 0.05) with weaning age; from 0% (LPP and HPP) for fry weaned at 15 DAH to a survival rate of 69.4% ± 3.9% (LPP) and 80.0% ± 9.4% (HPP) at 65 and 85 DAH, respectively. This was, however, lower than the survival rate obtained for the control (Artemia) which was 93.3% ± 3.33% at 85 DAH. The final mean weight, weight gain, and survival rate improved significantly (p  < 0.05) for fry fed the HPP diet compared to the LPP diet. All digestive enzyme activity decreased significantly with increasing fish age (p  > 0.05). Based on the results, it is recommended, that H. niloticus fry is maintained on live Artemia nauplii and provided with dry feeds high in LC-PUFAs (33.98 mg g⁻¹ diet) and PLs (12.96 mg g⁻¹ diet) from <65 DAH to obtain higher survival rates.

Ecytonucleospora hepatopenaei (EHP) is an obligate intracellular parasitic pathogen of shrimp, causing growth retardation and increased susceptibility to opportunistic infections. Currently, there are few reports on the prevention and treatment of EHP infection in shrimp, and research on its drug targets is limited. This article utilizes RNA interference (RNAi) technology to conduct knockdown verification studies on potential drug targets involved in EHP’s invasion mechanism and life cycle. Three target gene sequences from genome, and annotated as EhAQP1 (aquaporin 1), EhPTP2 (polar tube protein), and EhTK (thymidine kinase) were used to synthesize specific small interfering RNA (siRNA). These siRNAs were injected into EHP-infected shrimp, and the hepatopancreas was sampled at 12, 24, 48, and 72 h postinjection to verify the interference effect and spore load. The results showed that RNAi exhibits varying inhibitory effects on different genes and is time-dependent. For EhAQP1, interference was most effective in the early stages (12 to 24 h), while the interference effects for EhTK were more pronounced at 48 and 72 h, the expression of EhPTP2 was significantly downregulated (p < 0.001) only at 24 h. In the EhAQP1 and EhPTP2 interference group, the spore load decreased from 12 to 48 h, but increased at 72 h. In contrast, the EhTK interference group showed a continuous decrease in spore load from 12 to 72 h. In summary, this study provides a new strategy for prevention and treatment of shrimp EHP infection and lays the foundation for subsequent research on RNAi–based prevention and treatment of EHP infection.

An animal’s behavior can directly reflect its psychological or physiological condition. The in-depth understanding of fish behavior, especially reproductive behavior, is an important safeguard to promote sustainable aquaculture. In this study, we used the Posture-Act-Environment (PAE) coding system to construct an ethogram of Odontobutis potamophila to help people better judge and identify O. potamophila behaviors; and we designed two groups of experiments to figure out the individual factors affecting the reproduction of O. potamophila. These were the selection of female O. potamophila for male O. potamophila of different sizes, with or without nests, and with or without parental care behaviors, as well as the selection of male O. potamophila for female O. potamophila of different sizes. The results showed that we recorded 14 postures, 22 movements, and 29 behaviors of O. potamophila. Based on their biological functions, the recorded behaviors of O. potamophila were divided into nine types, that is, exploration, territoriality, attack, courtship, mating, parental care, ingestion, stationary behavior, and others. O. potamophila had nocturnal habits, and all the nighttime activities were significantly higher than those during the daytime (p < 0.001). The mating system of O. potamophila was polygamous, and the average mating duration for successful spawning was 9.99 ± 1.23 h. In mate choice experiments, both females and males spent significantly more time stationary than activity (p < 0.001). Females exhibited a slight preference for males with large individuals (strength of preference [SOP] = 53.46%), no nests (SOP = 50.51%), and no parental care behavior (SOP = 55.58%). The results of male mate choice were similar. Although the standard length of females was positively correlated with fecundity (r = 0.61), there were no significant differences in the number of male-to-female choices or duration of association (p > 0.05). This indicated that males showed no preference for larger or high-fertility females (SOP = 47.10%). Therefore, it is likely that males may not be selective for females with different fecundity levels. This study enhances the current understanding of the behavioral patterns of O. potamophila. It establishes a foundation for further research on its reproductive behavior and contributes to the advancement of captive breeding for this species.

This study investigated the toxicological impact of Voliam Flexi (containing chlorantraniliprole and thiamethoxam) on juvenile African catfish (Clarias gariepinus), a species commonly exposed to pesticides in rice cultivation regions. This study investigated the toxic effects of Voliam Flexi on juvenile African catfish, focusing on oxidative stress, antioxidant enzyme disruption, and tissue damage at environmentally relevant concentrations. Over a 15-day period, fish were exposed to environmentally relevant pesticide concentrations commonly applied in Egyptian rice fields, specifically 43.5, 87.5, and 175 mg/L. Antioxidant defense mechanisms, including GST (glutathione S-transferase), SOD (superoxide dismutase), CAT (catalase), and TAC (total antioxidant capacity), were measured alongside oxidative damage indicators such as lipid peroxidation (LPX) and DNA fragmentation. A dose-dependent reduction in antioxidant enzyme activity and an increase in oxidative damage were observed, with higher pesticide concentrations leading to elevated LPX levels and DNA fragmentation. Histopathological evaluations of the kidney and spleen revealed significant degenerative changes, such as tubular damage, edema, and pyknotic nuclei, particularly at higher concentrations. These findings suggest that Voliam Flexi poses considerable risks to aquatic organisms, disrupting cellular functions, and leading to tissue damage. The study highlights the potential threat of pesticide runoff to aquatic biodiversity and calls for stricter environmental regulations to mitigate these risks.

The microbiota of the gastrointestinal tract (GIT) plays a crucial role in the development, lifespan, physiology, barrier functions and immunity against pathogens in fish. One of the significant causes of fish mortality in production systems, which also generates huge financial losses, is pathogenic dieseases. Consequently, effectively managing disruptions in the microbiota could play a crucial role in mitigating economic losses across the sector. It was investigated the effect of an alternative raw material increasing inclusion—full-fat Hermetia illucens larvae meal on the composition of the gastrointestinal microbiome of Atlantic salmon. Thus, five experimental feeds were prepared: a control diet (CON) without the addition of black soldier fly full-fat meal (BSFM) and with 30% fish meal (FM); BSFM5, with 5% addition of full-fat BSFM and 27.1% FM; BSFM10, with 10% full-fat BSFM and 24.3% FM; BSFM15, with 15% addition of full-fat BSFM and 21.3% FM; and BSFM20, with 20% addition of full-fat BSFM and 18.6% FM. After 60 days of growth experiment on Atlantic salmon presmolts, the contents of two sections of the GIT, proximal and distal, were gently sampled and subjected to next-generation sequencing (NGS) to analyse the microbial populations. No significant differences were observed in the microbial compositions of the groups, irrespective of the intestinal section analysed. In the proximal and distal intestine, the CON group exhibited the highest number of distinct phyla. Increasing the inclusion of BSFM in the diet led to a reduction in the abundance of specific phyla. Similar results were noted at genus level. The BSFM5 and BSFM10 groups showed increase number in Enterococcus, while the Lactobacillus population were maintained at a high level. Due to abovementioned changes as well as the increased share of Bacilli populations, it may be concluded that up to 20% BSFM shares may have positive microbiota-modulating effects. Thus, BSFM may be considered not only as a nutrient source but a functional feed material in fish diets also, due to its prebiotic effects observed in the study.

Aquaponics systems integrate aquaculture and hydroponics to create a sustainable method for food production by recycling nutrients. However, nutrient waste management in aquaponics systems remains a challenge, particularly in achieving optimal growth for both fish and plants while minimizing environmental impacts. This study compared the effectiveness of raft and selected medium culture systems in removing waste from a small-scale aquaponics production system that included leafy vegetable crops (Brassica oleracea) and Nile tilapia (Oreochromis niloticus). The aquaponics systems comprised of four hydroponics systems: three media based (charcoal, perlite, and pumice) and one raft system in a completely randomized design. The crops were cultivated in the hydroponic units, while O. niloticus fingerlings were reared in the fish tanks for 22 weeks. To compare the various hydroponics systems, growth metrics for the fish (weight and length) and plants growth parameters such as leaf index and biomass, as well as nutrient analysis were monitored and documented. Physicochemical parameters of the culture water were also monitored. Fish grown in the perlite medium had significantly higher mean final length and weight compared to other aquaponics setups in the study (p < 0.05). Plants grown on pumice had significantly more total biomass than other media (p < 0.05) and had the highest crude protein (CP) content, while those planted on perlite had the highest crude lipid content (p < 0.05). The charcoal medium was the most effective, lowering total ammonia nitrogen (TAN) levels by up to 67.1%. Pumice showed the highest total suspended solids (TSSs) retention capacity (p < 0.05), resulting in a 25.9% drop in TSS levels. The raft system was the least effective at reducing aquaculture nutrient waste. This study demonstrated that the choice of hydroponics media is important in optimizing aquaponics systems for both plant and fish growth.

An experiment using a 4 × 3 factorial design was conducted to evaluate the impact of three commercial probiotics and a control (no probiotic treatment) on the growth, digestive, and immune enzymatic indices of prawns (Macrobrachium rosenbergii) at three stocking densities (2, 4, and 6 m⁻²). The experiment took place in rectangular earthen ponds with a surface area of 120 m² and a water depth of 1.5–2.0 m. The prawns in the treatment groups were fed commercial pelleted feed supplemented with probiotics. The results indicated a significant interaction effect on weight gain (WG), daily weight gain (DWG), daily growth rate (DGR), relative growth rate (RGR), specific growth rate (SGR), and survival. Overall, prawns treated with probiotics showed better growth performance compared to nontreated groups. Prawn cultured with P₁ at a stocking density of 4 m⁻² had better nutritional value, including higher protein level. The activity of prophenoloxidase (proPO), superoxide dismutase (SOD), and lipase enzyme was higher in probiotic-treated groups up to a stocking density of 6 m⁻² compared to control groups (p < 0.001). Probiotic P₁ at stocking densities of 2 and 6 m⁻² showed a significant interaction effect on the protease activity, with other probiotics also enhancing protease activity compared to control. This study highlights that the growth performance, proximate composition, protease, and lipase activity, as well as proPO and SOD activity, of prawns can be improved through the application of probiotic P₁. In conclusion, the study suggests that commercial probiotics enriched with bacterial compositions like P₁ can be effectively used for culture intensification of prawns.

Basil (Ocimum sp.) is a commercially important herb that has been coupled with several aquatic organisms in aquaponic systems. The goal of this literature review was to aggregate the current knowledge on the status of basil production in aquaponic systems by identifying the different aquatic organisms cultured with basil and hydroponic subsystems cultured with basil species/varieties and address research gaps. Of the 100 reviewed publications, about 90% of the reviewed publications used sweet basil (Ocimum basilicum L.) and only three publications used a different basil species; holy basil (Ocimum tenuiflorum), lime basil (Ocimum americanum), or lemon basil, (Ocimum africanum). Of the publications that used sweet basil, Genovese was the most commonly used variety (21 articles), followed by Italian large leaf (6 articles) and purple ruffles (4 articles) varieties. Between the reviewed publications, 38.7% used deep water culture (DWC), 31.1% used media bed (MB), and 17.9% used nutrient film technique (NFT) to grow basil. Tilapia was the most commonly cultured species with basil in aquaponic systems (44%), followed by catfish (14%) and carp (9%). The amount of feed for tilapia Oreochromis sp. cultured as a function of grow space area ranged between 20.3 and 81.6 g feed/m²/day. Values ranged between 29.2 and 68.9 g feed/m²/day while culturing Pangasius sp., 20–25 g feed/m²/day while culturing catfish (Ictalurus sp.), and 4.4–16.9 g feed/m²/day while culturing carp (Cyprinus sp.). The variability in the fish feed-to-plant ratio suggests a need for establishing a recommendation for a species-specific optimal feed input that supplies sufficient nutrients for basil. The current review suggests further investigations comparing different basil varieties, cultivating different basil cultivars with different fish or crustacean species, using alternative hydroponic types, and evaluating feed inputs for establishing a recommendation for species-specific optimal conditions in aquaponic systems.

Hyaluronic acid (HA) is a versatile polysaccharide with a broad range of biological, pharmacological, and therapeutic applications due to its anti-inflammatory properties, low immunogenicity, natural breakdown, compatibility with live tissue, and capacity to promote cell growth and specialization. However, the potential negative effects of HA on aquatic ecosystems, especially fish, have not been fully investigated. This study examines for the first time the potential physiological, immunological, and histological effects of HA in African catfish, as well as the long-term implications following recovery. Four groups, totaling 24 African catfish in triplicate, were subjected to varying concentrations of HA (500–100,000 µg/L) over a 15-day exposure period, followed by a 15-day recuperation phase, leading to physiological changes dependent on the dosage. The electrolyte levels in the plasma and the equilibrium of redox processes were significantly upset by exposure to HÀ. Fish exposed to high HA concentrations displayed dose-dependent declines in immunological function and antioxidant enzymes. Only the fish exposed to modest doses of HA showed complete recovery when compared to the control fish, indicating that exposure to HA resulted in irreversible alterations. The histological investigations showed a number of dosage-dependent pathological alterations in the renal and hepatic tissues, including perivascular and peritubular fibrosis, tubular necrosis, and vacuolar degeneration. The degree of these alterations varied according to the dose. Concluding that fish may have irreversible alterations as a result of high acidity. The present study provides a fundamental understanding of the detrimental effects of HA on fish. To fully evaluate the potential dangers associated with HA exposure and its long-term effects on aquatic life, more research is needed.

To explore the effects of temperature on the reproductive performance and embryonic development of female Eriocheir sinensis broodstock, the reproduction experiments of broodstock crabs under different temperatures (6, 9, 12, 15, 18, and 21°C) were carried out. Each temperature was replicated in three parallel tanks, with 5 male and 10 female crabs stocked in each tank for feeding. The results showed that with the rising of temperature, the mating rate of broodstock crabs increased gradually, the spawning rate, spawning amount, fecundity and reproductive index increased first and then decreased. At 15°C, the spawning rate, spawning amount, fecundity and reproductive index of the broodstock reached the highest and significantly higher than other temperature groups (p < 0.05). At 18°C, the egg diameter of embryos reached the largest. At 18°C, the contents of crude protein, triglyceride (TG) and total cholesterol (CHL) of embryos in E. sinensis were the highest. With the rising of temperature, the embryonic development rate of E. sinensis accelerated, the embryonic development time of the crabs was shortened and the effective cumulative temperature was gradually decreased. At 6°C, embryos stagnate at the fertilized egg stage, while at 9°C, they develop to the multicell stage but cease division thereafter. In conclusion, the best reproductive performance of the Chinese mitten crab was achieved at 15°C and the quality of embryos produced at 18°C was relatively good. The results of this study not only provided basic data for the breeding biology of E. sinensis but also provided scientific support for the conservation of fishery resources in the Yangtze River Estuary.