Aquaculture International最新文献

Recirculating aquaculture systems (RASs) are a sustainable aquaculture model strongly advocated by Chinese government. Earthy-musty is an important factor affecting the economic benefit and food safety of RAS. Geosmin (GSM) and 2-methylisobornyl (2-MIB) are the main substances that produce earthy-musty, which have a low human sensory threshold. Their accumulation leads to the earthy-musty of aquatic products, which greatly reduces the taste and economic value of these products and also threatens the sustainable development of aquaculture in China. GSM and 2-MIB are predominantly produced by heterotrophic prokaryotes in RASs. The production of these odorants is closely related to environmental factors, water quality parameters, and microbial community composition and is regulated by functional enzymes. Since the water exchange rate of RASs is only 5%, the current earthy-musty substances (EMS) treatment technology is not suitable for this system, and a cost-effective EMS removal technology is urgently needed. We put specific emphasis on the removal of EMS in RAS farms. Finally, we predict the challenges faced by EMS purification in RASs under the “comprehensive development of aquaculture” guideline by the Chinese government. In this review, first, we discuss the current GSM and 2-MIB generation mechanism in RASs, and then, based on the characteristics of RASs, we describe the transformation rules and removal methods of EMS in water systems and aquatic products, respectively. Finally, a new idea for removing EMS in RASs is proposed; that is, lipid adsorbents cooperate with functional microflora to remove EMS. This review provides scientific basis for eliminating the off-flavor of aquatic products, providing technical support for the promotion of RASs.

Graphical Abstract

This study evaluated the effects of interactions between β-glucan-enriched complex and vitamin premix on the zootechnical performance and histological and histomorphological parameters of the gastrointestinal tract of juvenile Nile tilapia (Oreochromis niloticus). The diets were supplemented with a manufacturer-indicated dosage of vitamin Premix at 1.5 kg ton feed⁻¹ (Vit_1.5 treatment) and with a high level of vitamin Premix at 2.0 kg ton feed⁻¹ (Vit_2.0 treatment), with or without the β-glucan-enriched complex added at a concentration of 5.0 kg ton feed⁻¹. Thus, the fish were subjected to four treatments: Vit_1.5 (control group), which consisted of individuals supplemented with the indicated level of vitamin Premix; Vit_1.5 + β-glucan group, which consisted of individuals supplemented with Vit_1.5 + β-glucan-enriched complex; Vit_2.0 group, which consisted of individuals supplemented with a high level of vitamin; and Vit_2.0 + β-glucan group, which consisted of individuals supplemented with Vit_2.0 + β-glucan-enriched complex. Twenty-eight experimental units with 40 fish each were used, totaling 1120 juveniles (2.5 ± 0.10 g and 4.9 ± 0.10 cm) fed for 30 days, and the data were collected at the end of the experimental period. There was an improvement in the final weight, final weight gain, and specific growth rate, as well as hepatic sinusoidal congestion, a mononuclear infiltrate, a decrease in microsteatosis, pyknosis nuclei, and melanomacrophage centers, a mononuclear infiltrate, as well as congestion in the spleen and an increase in the number of goblet cells and villi in the intestine. The interaction between β-glucans and vitamin premix in artificial diets for tilapia has been shown to improve zootechnical parameters, albeit slightly, and has led to the development of tissue adaptations in the gastrointestinal tract to improve nutrient absorption. However, pathological conditions were observed in the liver and spleen, and we suggest future research with longer feeding times and subsequent exogenous challenges to confirm these alterations.

Hepatopancreatic microsporidiosis caused by Enterocytozoon hepatopenaei (EHP) is an emerging parasitic disease causing great economic losses in almost all shrimp-growing countries. The disease is reported to be associated with severe growth retardation, size variation, and ultimately farm productivity. This study investigated the impact of various infection routes (viz. per os, cohabitation, water-borne and soil-borne) of EHP on disease progression. Per os (oral feeding) challenged shrimp acquired infection at a faster pace and could be detected in 100% of experimental shrimps by 5 days post-infection (dpi) as compared to 15 dpi by cohabitation method. The first detection of faeces of shrimp by water-borne infection was at 7 dpi compared to 15 dpi in the case of soil-borne infection. Soil- and water-borne infections were detectable in 100% of shrimps by 15 and 30 dpi, respectively. Nested PCR revealed a prepatent period of 5 days in case of oral and cohabitation challenge and 7 and 15 days in case of acquiring infection through water and soil sediments, respectively. Thus, a faster and higher level of infection was observed by oral challenge than other methods of infection. It could be inferred that the clinical course and pathogenicity of E. hepatopenaei infection at different time points is determined by the type of exposure, relative size group of the shrimp, and the quantum of infective spores (inoculum) ingested by the shrimp.

This research investigated the effectiveness of natural herbal supplements in reducing the harmful effects of heavy metals (HMs) toxicity on Cyprinus carpio (6.53 ± 0.01 g/fish). This study investigated the possible protective effects of natural herbal supplements on the growth, body composition, haematology, digestibility, and liver histopathology of common carp against the mixture of HMs. In phase 1, fingerlings were exposed to a mixture of HMs such as 100 µg/L lead acetate trihydrate/Pb (C₂H₃O₂)₂·3H₂O, 250 µg/L cadmium chloride anhydrous/CdCl₂, 800 mg/L zinc sulfate heptahydrate/ZnSO₄·7H₂O, and 2.5 mg/L copper sulfate/CuSO₄.5H₂O), and in phase 2, seven groups were established such as control positive group (CON + ve, HM exposure + without any treatment), control negative group (CON-ve, without HM exposure), and five groups with 1% turmeric (TUR), cinnamon (CUR), ginger (GIN), garlic (GAR), and their mixture (MIX), respectively. A total of 315 fingerlings were shifted to experimental tanks, i.e., 15 fingerlings per tank, and seven groups were made in triplicates. The results demonstrated that the carp exposed to HMs alone suffered detrimental health impacts. In contrast, when the fish were treated with natural herbal supplements, the MIX group exhibited noticeable positive improvements. In conclusion, the study suggests that natural herbal supplements are a potential solution to counteract HMs toxicity in C. carpio.

Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) causes substantial economic losses to the shrimp farming industry. Most research on EHP was focused on Penaeus vannamei due to its widespread farming and impact. The information on EHP infection in farmed tiger shrimp, Penaeus monodon, is scarce, especially considering its re-introduction and use of specific pathogen-free (SPF) seeds in India. A polymerase chain reaction–based (two-step PCR) survey targeting the spore wall protein (SWP) gene and SSU rRNA gene was conducted to understand the prevalence of EHP in P. monodon farms across six states, three each on the east and west coasts of India. While only 19 of 63 farms (30.15%) surveyed during the study revealed the presence of EHP using SWP-specific PCR, 38 farms (60.31%) were found to be positive with SSU rRNA PCR. Coast-wise, prevalence estimated using SWP-specific PCR showed 35% in the east and 21.7% in the west. However, only one of the farms showed EHP in the first step of PCR. The low level of infection, as indicated by the PCR analysis, was further validated and confirmed by histology and quantitative real-time PCR (qPCR). The EHP load ranged from 1.0 × 10³ to 3.7 × 10⁶ copies/µg DNA, and histology of the hepatopancreas showed only mild pathological changes and inclusion-like bodies similar to the developmental stages of EHP. Some of the samples showed bacteria-induced hemocyte infiltration and nodule formation. However, no microsporidian spores could be noticed in the histological sections. The phylogenetic analysis of sequences of SWP-specific PCR amplicons showed similarity with earlier reported EHP strains from P. vannamei from Thailand, Latin America, and India. A statistical epidemiological study to identify risk factors associated with HPM revealed the presence of EHP infection in previous cultures, the use of wild seeds and continuous farming as potential risk factors, and the use of SPF seeds and bleaching as protective factors. P. monodon is susceptible to EHP infection, yet the impact on the species is significantly lower than that reported in P. vannamei. The present report forms the latest data on the prevalence of EHP in P. monodon farms in India.

Probiotics have become an alternative in the aquaculture industry and are considered an environmentally friendly approach for disease control. However, the maintenance of the viability of probiotic bacterial cells during storage is quite challenging. This study aimed to investigate the potential effects of euryhaline probiotic and paraprobiotic B. cereus BR2 on African catfish, specifically on growth performance, gastrointestinal health, immune-related gene expression, and resistance to Edwardsiella tarda ETS1.1. The test feed was enriched with a 1% (w/w) dose of probiotics and paraprobiotics at a cell density of 10⁸ and 10¹⁰ CFU mL⁻¹, each with replications. For the diet supplementation experiment, African catfish fry with an initial average body weight of 6.67 ± 0.34 g were randomly placed into six aquaria containing 60 L of freshwater and reared for 30 days. Afterward, fish were challenged intraperitoneally on day 31st with E. tarda ETS1.1 at cell density of 10⁷ CFU mL⁻¹ and reared for 14 days. The results showed that diets treated with probiotics and paraprobiotics 10⁸ and 10¹⁰ CFU mL⁻¹ significantly (p < 0.05) increased mean final weight, mean final biomass, specific growth rate (SGR), disease resistance (survival rate), and reduced feed conversion ratio (FCR) values. Digestive enzyme (amylase, protease, lipase) activities were measured higher in supplementation treatments than in control fish. Furthermore, the immune-related genes IL-1β and MHC-2β expression significantly upregulated after supplementation. Post-challenge test, IL-1β showed the highest upregulation in DPI1 and downregulated in DPI 3 and DPI 7, while MHC-2β showed the opposite expression pattern, with the highest expression shown in DPI 7. The supplementation of probiotic and paraprobiotic B. cereus BR2 per oral effectively improved growth performance, digestive enzyme activity, immune-related gene expression, and resistance of African catfish to E. tarda ETS1.1.

Biofloc technology (BFT) has been identified as an effective and sustainable aquaculture method, particularly beneficial for warm-water species in tropical areas. This technology is widely used in intensive aquaculture for several aquatic species due to its capacity to significantly reduce water exchange rates, benefiting both production systems and the environment. The efficacy of BFT in farming operations is directly related to a proper management of water quality parameters within the optimal range of the target species, as these parameters directly impact the yield of production units. Essentially, BFT functions as a water quality management system, converting harmful nitrogenous waste such as ammonia and nitrite into less harmful forms such as nitrates through microbial activity, ensuring the health of aquatic organisms. Key environmental factors such as temperature, dissolved oxygen (DO), pH, salinity, alkalinity, TAN, nitrite, nitrate, settleable solids (SS), and total suspended solids (TSS) can affect the growth of aquatic species and the functionality of the microbial community. This review brings (i) a comprehensive bibliometric analysis on biofloc and water quality, (ii) highlights optimal ranges, and (iii) key observations of several water parameters including temperature, salinity, nitrogenous compounds, SS, TSS, DO, phosphate, pH, and alkalinity in BFT rearing conditions for key aquatic species. Elements such as countries, thematic and keywords, and authors were explored, correlated, and discussed. In addition, this manuscript also (iv) discusses the presence of heavy metals and microplastics (MPs) in BFT culture water. A dedicated review on water quality in biofloc technology will contribute to future research and development (R&D) in this topic, support decision-making to improve farming operations, and can help further expansion of BFT-based aquaculture.

The present study was designed to investigate the cytotoxic effects and bioaccumulation of heavy metals iron (Fe), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb), manganese (Mn), nickel (Ni), and chromium (Cr) in different parts (muscle, gills, and liver) of Tilapia zillii occurring in polluted drainage canal and fish farm, which is located in Abiece region in front of village number 10, Alexandria governorate, Egypt. Results of water analysis revealed the concentration of Cd, Pb, Mn, Ni, and Cr exceeded the limits defined by the American Public Health Association (APHA) in the polluted drainage canal. In addition, the concentration of Ni elevated to the standard limits of APHA and Cu was not detected in the fish farm. Different types of chromosomal aberrations were recorded (e.g., stickiness, fragmented chromosomes, centromeric gaps, chromatid break, chromatid deletion, and tetraploid). Micronucleus frequency was found to be 5.58 in the polluted drainage canal group and 0.32 in the fish farm group. Other nuclear abnormalities such as blebbed nucleus, segmented nucleus, enucleated erythrocyte, kidney-shaped nucleus, heart-shaped nucleus, polymorphic irregular nuclei, binucleated cell, nuclear fragmented erythrocyte, long nucleus, putative fragmented notched nucleus, lobed nuclei, fused erythrocytes, necrotic erythrocyte, and vacuolated nucleus were recorded. The total of erythrocytes nuclear morphological abnormalities was 70.33% in the polluted drainage canal and 1.78% in the fish farm.

This study investigated the influence of visual and chemical stimuli from live prey on juvenile Florida pompano (Trachinotus carolinus) growth. Twelve tanks within four independent recirculating systems housed fish of similar weight (obtained from a commercial fish farm) in groups of ten. Prior to their morning feeding (they were fed twice daily at 10 h and 16 h with commercial pellets), fish were exposed to one of four stimuli: visual and chemical cues from Artemia, mole crab, feed pellets (control for stimuli), or seawater (control for procedures). Key growth parameters were monitored weekly for seven weeks, including feed intake, weight gain, and specific growth rate (SGR). Fish exposed to Artemia and mole crab stimuli exhibited significantly higher feed intake (23.11 ± 1.37 and 23.45 ± 1.38 g/fish), weight gain (169.28 ± 7.59 and 172.75 ± 12.57%), and SGR (2.02 ± 0.05 and 2.04 ± 0.09% day⁻¹) compared to those exposed to feed pellets (stimuli control) and seawater (procedures control): feed intake (20.81 ± 0.684 and 19.30 ± 0.39 g/fish), weight gain (136.25 ± 4.51 and 140.23 ± 6.36%), and SGR (1.75 ± 0.03 and 1.78 ± 0.05%.day⁻¹). These findings highlight the importance of visual and chemical cues from live prey as feeding incitants and stimulants. By enhancing feeding motivation and intake, these stimuli promote growth and potentially improve the welfare of juvenile Florida pompano.

The aquaculture industry is suffering from significant financial setbacks due to an increasing frequency of disease outbreaks, posing a threat to the sector’s sustainability. Various bacterial, viral, parasitic, and fungal pathogens have led to massive mortalities in farmed fish worldwide. Throughout the years, the management of fish diseases has predominantly centered around the utilization of conventional antibiotics and chemicals. Nevertheless, their indiscriminate use has given rise to serious implications, including an increase in resistant pathogens, disruptions in the metabolic processes of fish, degradation of the aquatic environment, the presence of drug residues in aquatic products, and a potential threat to human health. Various effective bio-based and immunoprophylaxis alternative therapies have been developed to overcome these impediments. Recent alternative therapeutic approaches to fish diseases encompass a range of strategies, including phytotherapeutics, nanotherapeutics, probiotics, prebiotics, synbiotics, phage therapy, vaccination, quorum quenching, antimicrobial peptides, biosurfactants, bacteriocins, stem cells, and diagnostic-based therapy. Advancements in biotechnology have significantly enhanced the efficacy of these therapies. However, additional research is essential to refine the utilization of these therapeutic approaches. Critical concerns, such as efficacy, cost, risks, availability, and adverse effects on fish and the ecosystem, need to be addressed to establish guidelines for their sustainable application in aquaculture. This review will increase aquaculturists’ awareness of recent therapies used in fish farming, their mechanisms, challenges, and impacts while promoting the sustainability of commercial aquaculture.