Monitoring stress in fish by applying image analysis to their skin mucous cells

Little attention has been paid to the effects of fish microbiotas on the reproducibility and comparability of fish studies so far. Extrinsic and intrinsic factors, such as water quality, environmental microbial populations, diet, host genetic profile, gender, age and stress status, affect fish microbiotas and create significant inter- and intra-species variations. Fish microbiotas play critical roles in many key aspects of host physiology, such as protection against pathogens, digestion and development of the digestive tract and the local immune system. Thus, greater effort should be invested in standardizing the microbiological profiles of research fish. In this context, issues requiring consideration include the establishment of isogenic and isobiotic fish lines, the standardization of rearing conditions and the development of appropriate tests to adequately describe microbial populations. There are many challenges involved in each of these issues, and the research community must decide which aspects should be standardized for each species and each type of research. For all studies in which microbiota is expected to exert an influence, thorough reporting is of paramount importance. Every step towards standardization increases study quality and simultaneously contributes to reducing the number of fish used in research, which is a legal and ethical obligation.

The present study examined the efficacy of dietary selenium-enriched spirulina (SeE-SP) on growth performance, antioxidant response, liver and intestinal health, immunity and disease resistance of Asian seabass, Lates calcarifer. A total of 480 seabass juveniles with an initial weight of 9.22 ± 0.09 g/fish were randomly assigned to four dietary groups. The fish were fed a fishmeal protein replacement diets with SeE-SP at 5%, 10%, and 20%, namely SeE-SP5, SeE-SP10, and SeE-SP20, and a fishmeal-based diet as control for 8 weeks. The results indicated that seabass juveniles fed SeE-SP5 and SeE-SP10 diets grew at the same rate as the fish fed a fishmeal-based control diet after 8 weeks of feeding, while SeE-SP20 grew at a significantly lower rate than the control (p < 0.05). Although most of the measured biochemical parameters were not influenced by the Se-SP diets, serum antioxidant-enzyme glutathione peroxidase (GPx) and immunological indices, such as lysozyme activity and immunoglobulin-M, were found significantly higher in the SeE-SP5 and SeE-SP10 diets compared to control. In addition, the fish fed the SeE-SP5 diet showed significantly lower mortalities after the 14-day of bacterial challenge with V. harveyi. These outcomes indicated that up to 10% inclusion of SeE-SP in the diet of juvenile Asian seabass does not compromise growth, while SeE-SP5 enhanced disease resistance in juvenile seabass.

This study analyzed and compared the nutritional profiles of wild (Pangasius pangasius) and farmed (Pangasius hypophthalmus) pangasius catfish collected from the various sources of river and culture ponds in Bangladesh. The results indicated that the wild pangasius catfish had a significantly (p < 0.05) higher levels of moisture, fat and ash content, compared to the farmed one. However, the farmed pangasius had significantly higher level of protein and carbohydrate, compared to wild pangasius. The total EAA ratio was found to be significantly higher (p < 0.05) in wild pangasius (1.51 ± 0.01 g/100 g), compared to farmed pangasius (1.55 ± 0.01 g/100 g), which exceeded the FAO/WHO minimum standard of 40% for both species. In regard to fatty acid contents, wild pangasius was found to be rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) with a mean value of 4.89% and 2.72%, respectively, while the values in the farmed pangasius were 1.07% and 0 (not detected), respectively. A higher ω-3/ω-6 ratio was found in wild pangasius 14.26%, in comparison with farmed pangasius (0.14%). Overall, the results indicated that pangasius catfish either farmed or wild are suitable for human consumption wherein wild pangasius has superior amino acid and fatty acid quality, compared to the pangasius reared in captivity.

This study tested drugs and therapeutic compounds to determine effective commercial treatment for fishes infected with myxosporeans. Two series of shore-based experiments and 1 field trial were performed. For the shore-based experiments we used Puntazzo puntazzo (ca. 20 g weight) with kidneys infected with Myxobolus sp. Initially, 6 different doses of Fumagillin, 2 doses of Toltrazuril, and 1 dose of Amprolium, ESB3 and Salinomycin were tested. In the second shore-based experiment, infected fish were treated with Origanum essential oils, Toltrazuril with propylene glycol, Amprolium, and a combination of Salinomycin 12% + Amprolium (SA). In the field trial, P. puntazzo (ca. 165 g) infected with the parasite were treated with SA, Origanum essential oils and Fumagillin. In all trials, the drugs were added to the feed and administered according to the selected regimen. Their efficacy was evaluated in terms of mortality (acceptable level was 6 mg kg(-1) body wt for 6 wk in the interstitial renal tissue, where slight inflammation arose. The highest dose tested (25 mg kg(-1)) also produced necrosis in the interstitial tissue, degeneration of the epithelial cells of the tubules and a reduction in melanomacrophage centre numbers. The SA combination proved the most effective treatment for Myxobolus sp. infection of P. puntazzo as (1) the therapeutic regimen and commercial product was not toxic and (2) a significant reduction occurred in the prevalence rate.