Springer Science and Business Media LLC

Neozoa are invasive species that enter faunal communities as new species. Not infrequently, they pose a threat to local ecosystems. Climate change could further promote these developments or favor neozoa. Thus, they represent a relevant threat in the future. One of these neozoa is the copepod parasite Mytilicola orientalis. This parasite originates from Asia and infects a wide variety of bivalves like mussels and oysters. However, as an invasive species, it can be found more and more frequently in Europe, especially in the North and Baltic Seas. There, M. orientalis poses a real threat to mussels in aquaculture and thus also to the local economy.

Ammonia nitrogen is an unavoidable factor in aquaculture, and it may have a severe effect on clam breeding. To explore the toxic effect of ammonia nitrogen on the clam Cyclina sinensis, the clam was exposed to ammonia nitrogen (8.07 mg/L) for 768 h (32 days) and then challenged with Vibrio parahaemolyticus. During the exposure, the hydrolases (acid phosphatase, ACP; alkaline phosphatase, AKP; lysozyme, LZM) and the interleukin 17–3 (IL-17–3) gene were assessed. The result showed that during ammonia nitrogen exposure, the activity of ACP in the hepatopancreas showed an overall upward trend, and the activity of AKP and LZM showed a trend of increasing first and then decreasing. Following infection with V. parahaemolyticus, all the hydrolases activities fluctuated in 144 h. The full-length IL17-3 cDNA is 1027 bp in length and contains a 144-bp 5′-untranslated region (UTR), a 284-bp 3′-UTR with a poly (A) sequence, and an open reading frame (ORF) of 603 bp encoding an IL17-3 protein of 200 amino acids with a deduced molecular weight of 21,986.7 Da and a theoretical isoelectric point of 6.57. The expression of IL-17–3 m RNA was detected in all selected tissues of the clam. At the onset of ammonia nitrogen stress, the expression of IL-17–3 was significantly upregulated in the hepatopancreas of C. sinensis, and reached the maximum value at 6 h. Following infection with V. parahaemolyticus, the expression of IL-17–3 in the hepatopancreas was also significantly upregulated, and reached the maximum value at 48 h. Our study may provide the first evidence of the role of the main hydrolases and IL-17–3 in clam responding to ammonia nitrogen stress.

The economic and ecological effects of three shrimp farming models commonly adopted in China, including the indoor super-intensive culture model (ISIC), the pond integrated multi-trophic aquaculture model (PIMTA), and the pond mono-culture model (PMC) were evaluated in this study. The economic and ecological effects of the three models were quantitatively estimated using a series of statistical analyses. The break-even analysis of the three models indicated that the unit output of ISIC and PMC was comparatively higher than others. Meanwhile, the variable cost of ISIC and PMC was much higher than the fixed cost, while PIMTA presented the opposite result. However, the cost-benefit study showed that PIMTA had the greatest profit margin. Regarding ecological effects, the comparison of water quality factors and pollutant emissions indicated that the PIMTA model could comparatively decrease the nitrogen and phosphorus discharge from aquaculture sewage and prevent water eutrophication. Moreover, PIMTA led to a higher bacterial diversity than ISIC. Furthermore, the analysis of the carbon sink capacity of the three cultivation modes showed that the PIMTA model had the highest carbon sink capacity of 812.21 g kg−1. When PIMTA shrimp production is 0.72 times higher than the total production of ISIC and PMC, the goal of zero CO2 emissions can be achieved. By combining ISIC high-density farming with PIMTA ecological farming, companies can effectively balance the ecological damage caused by shrimp farming by adjusting the ratio of ISIC and PIMTA while addressing the market demand for shrimp.

This study describes growth variation within groups of salmonids and the relation to initial fish weights and feeding levels. PIT-tagged rainbow trout (RT) and brook trout (BT) of start weight 120–170 g were reared in separate tanks for 9 weeks. Both species were fed each day either a high ration close to satiation (H) or half of this ration (L). Four experimental groups (RT-H, RT-L, BT-H, BT-L) were studied with regard to their propensity to increase weight in accord with their initial weight. The slope of the regression line between initial weights (g) and weight increases for individuals in each tank in each period was applied as indicator for this propensity (termed “slope”). All calculated slopes in the experiment were positive which indicates the general ability of weighty fish to gain more weight than smaller individuals. The average slope during all 9 weeks was 2–4 times higher for RT-L (5.91) than for all other groups (RT-H: 1.50, P < 0.01; BT-H: 1.76, P < 0.01 and BT-L: 2.88, P < 0.05), indicating the particular propensity of large RT to gain weight when feed was restricted. Overall, ration level had large impact on slopes (H: 1.63, L: 4.39, P < 0.01), while this was not the case for species (RT: 3.71, BT: 2.32, P > 0.05). The magnitude of slopes decreased over time (weeks 0–3:4.27, weeks 3–6:3.02 and weeks 6–9:1.74, P < 0.05). The observed differences in weight gains between experimental groups were reflected in differences in coefficients of variations (CVs) for body growth. RT had larger body weight (BW) CVs compared to BT (0.257 vs. 0.206, P < 0.01) indicating more uneven feed share among RT than among BT in general. RT-L had significantly higher BW CVs than all other groups (0.300 vs. 0.184–0.229, P < 0.01). The observed differences in weight gains enhance size variations in terms of higher CVs, and this may have implications for feeding tactics in aquaculture where large size variations in groups may be disadvantageous to fish farmers.

The yolk utilization rates and effects of delayed initial feeding were examined on the feeding ability, survival and growth of the larvae of two freshwater species, rohu, Labeo rohita and singhi, Heteropneustes fossilis reared in the laboratory at 26 (2) °C. Although the yolk reserves in both species lasted at least 7 days after hatching, all larvae initiated feeding by the fifth day, indicating a short period of mixed (endogenous and exogenous) feeding. When first feeding was delayed beyond the fifth day, subsequent weight gains and survival rates declined progressively for both rohu and singhi, although their feeding abilities were not adversely affected until the seventh (singhi) and eleventh (rohu) day. The point of no return (PNR) (when 50% of the unfed larvae were unable to feed when offered food) was reached in singhi when they were 8 days old and in rohu when they were 14 days old. Even among the larvae that fed at PNR, their subsequent mortality rate was nearly 100%, reflecting the irreversible effects of starvation. This study showed that rohu were more resistant to starvation than singhi.

Aquaculture and the production of aquatic goods are rapidly growing industries in the world. These industries involve the cultivation of various saltwater and freshwater fish as well as shellfish species, and they undergo regular updates in their manufacturing processes. The increasing popularity of aquaculture is driven by the desire to achieve long-term sustainability in food production. However, the intensification of farming techniques can lead to economic losses due to fish mortality, which is often caused by infectious and stressful conditions. To address this challenge, it is crucial to enhance the immune response of fish as part of sustainable intensification and aquaculture management. Recently, there has been growing interest in eco-friendly and natural bioactive solutions as potential alternatives to synthetic compounds used for disease prevention in aquaculture. Medicinal plants, available as whole plants, plant extracts, or synthetic analogues of natural substances known as phytomedicines or phytopharmaceuticals, have shown high efficacy in disease prevention for humans and animals. One such medicinal plant is Saussurea lappa, which is extensively utilized in various forms of medicine for treating multiple diseases. The bioactive chemicals derived from S. lappa exhibit a wide range of biological activities, including anti-inflammatory, antioxidant, antimicrobial, and anticancer properties, along with immunostimulatory effects. Given the diverse biological activities of S. lappa and its potential to enhance the immune responses of aquatic species, this review focuses on exploring its contributions in this area. By examining the numerous benefits and applications of S. lappa, we aim to shed light on its potential role in improving the immune response of aquatic species.

The use of phytobiotic as functional feed additives is a promising inducer for growth performance and immune response in the Pacific whiteleg shrimp (Litopenaeus vannamei). It can be also commercially applied in combination with chemotherapeutic agents and vaccines. This study was carried out to evaluate the use of a commercial phytobiotic feed additive, Sanacore® GM, containing vegetable fatty acids and inactivated Saccharomyces cerevisiae with herbal extracts, on growth, body composition, non-specific immune response, antioxidant index, intestinal microflora count, and fungal resistance to Fusarium solani challenge in Pacific white shrimp, Litopenaeus vannamei. Shrimp juveniles (5.00 ± 0.1 g) were randomly distributed into 12 hapas (1 m3) in triplicates at a stocking density of 20 shrimp per hapa and fed increasing levels of Sanacore® (0, 0.1, 0.2, and 0.3%) for 63 days. At the end of the feeding trial, the experimental shrimp were infected with F. solani, and mortality was recorded for 15 days. Results revealed that growth performance, feed utilization, and whole-body protein deposition were improved with increasing dietary sanacore levels. A significant improvement was reported in cellular (hemocyte counts, phagocytosis, phagocytic index, respiratory burst activity) and humoral (lysozyme and phenoloxidase) immune responses with higher dietary sanacore levels. Superoxide dismutase, catalase, and glutathione peroxidase were notably improved in shrimp-fed sanacore-supplemented diets. Meanwhile, malondialdehyde level was significantly decreased in all sanacore-supplemented shrimp. Furthermore, the dietary sanacore consistently increased probiotic bacterial counts and decreased enteric and Clostridium sp. counts in the intestine. Juveniles fed with Sanacore exhibited significantly lower mortality rates when challenged with F. solani. In conclusion, dietary sanacore could exhibit a profitable effect on the growth performance, antioxidant capacity, immunity, intestinal microbial, and the health condition of L. vannamei. Thus, sanacore can be used as an attractive feed supplement in the L. vannamei diet (0.2–0.3%), providing more insights into its application in aquaculture as a functional immunostimulant feed additive.

Megalocytivirus of family Iridoviridae has been identified as a pathogen that caused the fatal systemic infection to lead to massive death of numerous fish species in both ornamental and food fish industries. It caused significant economic losses due to severe mortality of infected fish. Since 2011 in Indonesia, megalocytivirus in giant gourami (Osphronemus goramy) had been found as the main pathogen in some cases of giant gourami outbreak, especially in West Java, Central Java, and Bali. The aim of this study is to identify and characterize the pathogen known as a megalocytivirus infection in freshwater-cultured giant gourami. We identified the virus using universal and specific primers for megalocytivirus and infectious spleen and kidney necrosis virus (ISKNV). Sequencing and BLAST analysis were used to develop a phylogenetic tree. The result showed that phylogenetic analysis of major capsid protein (MCP) gene unveiled a new member of megalocytivirus, designated as giant gourami iridovirus (GGIV). GGIV-formed cluster belonged to ISKNV and has 100% homology to ISKNV complete genome. Artificial infection by intraperitoneal injection with supernatant homogenate from spleen and kidney of naturally infected fish showed 93% cumulative mortality in 12 days. Fish showed a clinical sign of infection as lethargic, loss of appetite, pale or darken body color, and hemorrhages. Internal organ on dead fish showed swollen spleen and kidney and also a pale liver. Quantitative PCR analysis on internal organs showed spleen had the highest viral DNA copy number followed by kidney, gill, and liver. Histopathological analysis showed many abnormally hypertrophied cells in spleen which is typical histopathological characteristic of megalocytivirus infection. In conclusion, GGIV belonged to ISKNV from genus megalocytivirus.

The present study was conducted to evaluate the interaction of protein and energy ratio in low protein (20, 25 and 30 %) diets for juvenile Nile tilapia (Oreochromis niloticus) (initial weight 7.44 ± 0.03 g). Dietary protein to energy (P/E) ratio of nine practical diets ranged from 66.84 to 115.14 mg protein/kcal energy. Each diet was randomly assigned to four replicate groups of fifteen fish. After 10 weeks, Fish fed the lowest dietary protein (20 %) and lowest energy (2,600 kcal/kg) diets were significantly smaller than fish maintained on D5 (25/2800) and D6 (30/2800), However, there were no significant differences among all the treatments except D1. The whole body moisture and protein levels were significantly influenced by dietary protein and energy content. Whole body energy content and digestible energy retention were significantly influenced by energy content of the diet. Conversely, dietary protein level significantly influenced protein retention but it did not influence digestible energy retention. Under the reported conditions, the response of tilapia to dietary energy or protein was seen only at the lower levels of inclusion and tilapia demonstrated limited protein sparing as dietary energy was increased. However, this did modify the carcass composition through higher dietary energy.