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The common use of antimicrobials in food-animal production can lead to drug residues in edible tissues for consumers. However, immunomodulators enhance immune responses and vaccine effectiveness. A new perspective explores bacterial extracellular bioactive molecules (EBMs) in food-animal production to modulate host immune responses, potentially transforming pathogen management and antimicrobial use. This study investigates the immunogenic potential of Aeromonas hydrophila-derived EBMs (Antigens) to enhance the immune system. Four Antigens were administered intraperitoneally to Oreochromis niloticus (Nile Tilapia). Antigens 2 and Antigens 3 boosted fish immune competence within 21 days. Remarkably, Antigens 3 induced robust immunity against A. hydrophila with a single dose, notably enhancing antibody-based immune responses. The increased antibody activity suggests Antigens 3 could be a vaccine candidate, promising further research and potential application in food-animal production to improve disease control. This study highlights immunomodulators' potential in reshaping disease management in the food-animal industry, emphasizing the benefits of focusing on bacterial EBMs to reduce reliance on antimicrobials and achieve sustainable disease prevention.

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Genetic relationships were examined for a total of 90 individuals of 90 species or species var. from 13 genera of Malawian cichlids based on the sequences of an amplified 991-bp fragment of the mtDNA control region (mtDNA-CR). In the network analysis, no exclusive clades were made by all the members of any genera in this study. However, congeneric clades were observed by genera Buccochromis, Copadichromis, Protomelas, and Sciaenochromis, whereas no congeneric clades were observed by genera Mylochromis, Nimbochromis, and Otopharynx. In non-mbuna, an Aulonocara-Lethrinops group was divided into two groups, and the mean genetic distance of the larger group was much lower from mbuna than from other non-mbuna. Overall mean genetic distance within a genus was generally low in mbuna, whereas it was relatively high in non-mbuna. In the genetic tree of each genus, two or more large clades were observed, and some clades, such as those of Aulonocara hansbaenschi and Aulonocara nyassae in genus Aulonocara, Lethrinops micrentodon and Lethrinops sp. "gold harbor" in Lethrinops, and Otopharynx ovatus and Otopharynx brooksi in Otopharynx, were very deeply differentiated. Besides, a mbuna species, Pseudotropheus crabro, was extremely deeply differentiated from other members of this genus. These results suggest a widespread morphological convergence across the taxa in parallel with deep genetic differentiation in the long evolutionary story and some possibility of generation of the species of Aulonocara-Lethrinops group by hybridization of small non-mbuna and mbuna species. Furthermore, taxonomical reexamination is necessary based on a strong support by genetic connection.

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Marine fish are high in essential omega-3 fatty acids, which are important for human health. This study evaluated the effects of four extraction methods (soxhlet extraction, SE; wet rendering, WR; acid silage, AS; microwave-assisted extraction, MAE) on the oil yield, physicochemical properties, fatty acid profile, and nutritional quality index (NQI) of pangus fish oil. The oil yield ranged from 13.50% to 21.80%, with MAE having the highest yield. Furthermore, MAE oil has the lowest free fatty acid (0.70%), peroxides (2.08 Meq/kg), and saponification (287.27 mg/g KOH) value. There were no significant differences (p > .05) in the refractive index and melting point of oils among extraction techniques. A total of 25 fatty acids were identified. However, the maximum PUFA, MUFA, and SFA recovery was observed in the SE (19.15 mg/100 g), MAE (7.99 mg/100 g), and AS (17.33 mg/100 g), respectively. In terms of NQI, SE had higher PUFA/SFA, HH, and LA/ALA ratios, while AS had higher EPA + DHA, n-3/n-6, AI, TI, and FLQ indices. Furthermore, the MAE approach yielded better ratios of n-3/n-6 and HPI index, whereas the WR method yielded a higher AI index. Therefore, MAE would be the most efficient method for extracting pangus fish oil by considering both technical feasibility and quality indices including extraction yield, best physical properties, oxidative stability, and fatty acid contents.

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The fastest-growing aquaculture industry relies heavily on animal protein, fishmeal and plant protein to maintain production levels. Therefore, present study was conducted to perceive the effectiveness of blanched moringa (Moringa oliefera) leaf meal (MLM) as a replacement of soybean meal in silver barb (Barbonymus gonionotus) fingerling diet. Four experimental feeds were prepared replacing soybean meal with MLM at 0, 10, 30, and 50%. Fish were reared for 60 days in 12 hapas installed in three similar size and shaped ponds comprising four treatments each having 3 replications. Fish were fed with the experimental diet at 5% body weight twice daily. Fish growth parameters and length-weight relationship were assessed. To determine their resistance to stressful conditions, the fish were submerged in low pH-5 solution at the conclusion of the experiment. According to the results of the fish growth metrics, the majority of the parameters were comparable and statistically insignificant between the treatments. However, when compared to the control, T1 and T2 treatments, the T3 treatment demonstrated increased survival, PER, and fish production. In addition, other parameters such as percent weight gain, SGR, FCR and FCE were higher in control but statistically similar with T3. Besides, the length-weight relationship of silver barb fingerlings fed with all the test diets showed a positive association and isometric growth pattern. With the incremental addition of MLM to the fish diet, the hematological parameters-red blood cells (RBC), white blood cells (WBC), hemoglobin (Hb), and mean corpuscular hemoglobin (MCH) gradually increased. The fish fed the T3 diet had the highest recorded stress tolerance (6.50 ± 0.50 min), whereas the fish on the control diet had the lowest (T0, 4.77 ± 0.68 min). According to the study, MLM has the potential to replace soybean meal in the diet of silver barb fingerlings to the tune of 50:50 without having an adverse impact on growth. It can enhance fish hematological performance and tolerance for unfavorable environmental conditions as well.

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Monthly sampling of freshwater shrimps infested by the corallanid ectoparasite Tachaea chinensis was conducted at an agricultural canal of the Etsura River system, Shiga Prefecture, Japan, from April 2018 through December 2019. A total of 944 Palaemon paucidens and 279 Neocaridina spp. were collected, and 203 immature T. chinensis were found attached to the carapace of these hosts. Mean prevalence was 23.1% for P. paucidens and 6.4% for Neocaridina spp. Newly hatched T. chinensis ectoparasitizing P. paucidens were detected in August 2018 (minimum body length of parasite 3.2 mm) and appeared continually until June 2019 (maximum body length of 10.3 mm) and were not observed in July. In contrast, T. chinensis on Neocaridina spp. were first detected in August of each year (with minimum body length of 2.0 mm) and were observed until September in 2018 and to November in 2019 (maximum body length of 5.8 mm). Ratios of the body length of T. chinensis to the carapace length of the host shrimp were almost constant (0.8-0.9) with the host species and parasite growth. Although infestation by early-life-stage individuals of T. chinensis was observed on both shrimp species, P. paucidens appeared to be the principal host for individuals larger than 6 mm in body length.

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This study was conducted to evaluate the ambient water bacterial dynamics and its influence on the gut of resident teleosts; Oreochromis niloticus. The bacterial communities in the ambient water and the gastrointestinal tract (GIT) of O. niloticus were profiled using a culture-dependent method and followed by the 16S rRNA gene sequencing. The results indicated bacterial phyla of Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes respectively between the two microbial consortia. However, the relative abundance among the bacterial phyla notably differed between the two consortia. The relative abundance of Proteobacteria (≤ 67%) was dominant in both consortia, but contrarily, Actinobacteria and Bacteroidetes were higher in the ambient water relative to the GIT which indicated Proteobacteria and Bacilli as the highest diversity. Nevertheless, the relative abundance of γ-proteobacteria and Bacilli remarkably dominated both consortia at the class level, with Bacillus and Pseudomonas being the most abundant operational taxonomic units (OTUs).

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AIMS: The present study evaluated the antimicrobial activities of the medicinal plant Mallotus japonicus against the fish pathogenic bacteria, Aeromonas hydrophila, Aeromonas salmonicida, Edwardisella tarda and Vibrio anguillarum, and also describes the antimicrobial activities of the major and minor active compounds present within the plant extract. The synergistic effects by way of combination of these compounds were also evaluated and described. Chemical constituents of the plant extracts were analysed using the liquid chromatography-mass spectrometry (LC-MS) and described. METHODS AND RESULTS: The diethyl ether-extract of the plant elicited the strongest antibacterial activity against the challenged bacterial species, followed by ethanol- and methanol-extracts. The major active compound of the extracts, bergenin, demonstrated no antibacterial activity, but other compounds in the extracts did. CONCLUSION: Mallotus japonicus could be used as a prophylaxis to treat bacterial disease infections of fishes and its diethyl ether-extract has the potential of an alternative to antibiotic treatment in aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: Mallotus japonicus diethyl ether-extract has the potential of an alternative to antibiotic treatment in aquaculture.

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