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• Biodiversity and Depth-Related Species Distribution of Coral Reef Fish on the Seamounts of Tho Chu Archipelago, Vietnam

  Nguyen Van Thanh, Nguyen Khac Bat, Tran Van Huong, Pham Tran Dinh Nho, Hoang Dinh Chieu, Nguyen Viet Nghia

  Received: Apr 01, 2026 / Accepted: May 20, 2026 / Published: Jun 30, 2026

   Abstract PDF

  This study provides the first comprehensive assessment of the species composition and distribution of coral reef fish populations on the seamounts of Tho Chu Archipelago. Surveys were conducted during the Northeast monsoon (December 2023) and Southwest monsoon (July–August 2024) seasons across 24 transects spanning depths 11-30m. A total of 83 species from 45 genera, 23 families, and 13 orders were recorded. The most abundant families were damselfishes (Pomacentridae) with 19 species and wrasses (Labridae) with 15 species. Species richness was the highest in the shallow reef crest (11-15m; 70 species) and declined markedly toward the deeper reef foot (26-28m; 18 species). The overall diversity was high (H’ = 4.93), with a relatively even species distribution (J’ = 0.77). Mean fish density reached about 250 individuals per 500 m2, dominated by small-size fishes (< 10cm in total length). The Bray-Curtis similarity index revealed distinct depth-related groupings, with strong overlap in mid-depth communities. The findings provide baseline ecological data on species composition, density, and depth-related distribution patterns, serving as scientific evidence for marine conservation planning and sustainable fisheries management in offshore waters.

• Effect of Dietary Supplementation with Fermented Betel Leaves (Piper betle) on Growth Performance, Feed Utilization, and Disease Resistance in Common Carp (Cyprinus carpio)

  Nguyen Thi Mai, Dang Hoai Thuong, Le Xuan Chinh, Nguyen Thu Hang, Mai Van Tung

  Received: Dec 25, 2025 / Accepted: Feb 25, 2026 / Published: Jun 30, 2026

   Abstract PDF

  This study evaluated the effects of dietary supplementation with a fermented betel leaf preparation on the growth performance, feed utilization, and resistance to Aeromonas veronii infection in common carp (Cyprinus carpio). A six-week feeding trial was conducted using four diets: PF0 (control), PF2 (2 g kg-1), PF5 (5 g kg-1), and PF10 (10 g kg-1). After the feeding period, fish were challenged with A. veronii, and the cumulative mortality rates were recorded over 14 days to assess disease resistance. The results showed that supplementation at 10 g kg-1 significantly enhanced growth performance, while the feed utilization indices did not differ among treatments. Survival during the feeding period remained 100%, indicating that the fermented preparation was safe for fish. The PF10 group exhibited the lowest cumulative mortality (22.73%), followed by PF5 (35.38%), with both values significantly lower than the control (46.67%), demonstrating the immunoprotective potential of the fermented product. Overall, the findings indicate that the dietary inclusion of fermented betel leaves, especially at 10 g kg-1, can improve growth, maintain the feed conversion ratio, and enhance resistance to A. veronii infection in common carp, contributing to safer and more sustainable aquaculture practices.

• The Effects of Short Freshwater Bath Treatments on the Susceptibility to Different Stages of Neobenedenia girellae Infecting Barramundi (Lates calcarifer)

  Truong Dinh Hoai, Trinh Thi Trang, Nguyen Thi Huong Giang

  Received: Jun 09, 2019 / Published: Dec 24, 2019

   Abstract PDF

  Neobenedenia girellae is one of the most pathogenic parasites affecting marine fish in captivity conditions. The use of chemicals for parasite prevention and treatment have several benefits; however, they can cause various negative side-effects. In an effort to discover cost-effective and sustainable practices, our current study was aimed at investigating the efficiency of freshwater treatments on N. girellae. A challenge test was conducted to produce infected fish which became materials for the freshwater immersion experiments. The duration and reaction of the parasites at different development stages from eggs to adult parasites were examined. Our findings revealed that 100% of the adults and oncomiracidia of N. girellae were killed quickly in freshwater. The eggs of N. girellae, however, were highly resistant to freshwater with a hatching success rate of more than 95% in all the freshwater immersion treatments (2, 5, 10 and 30min). The eggs hatched mainly on day 7 and finished hatching on day 8. Thus, the freshwater immersion method can be applied to treat N. girellae at most stages excepted for the egg stage. The best practical treatment for this parasite is to perform a replicated immersion recommended 8 days following the first treatment.

• Growth Performance and Immune Response of Striped Catfish as Affected by Dietary Pro-, Pre-, or Synbiotics Derived from Lactobacillus sp.

  Nguyen Thi Mai, Do Thi Ngoc Anh

  Received: Apr 27, 2025 / Accepted: Jul 28, 2025 / Published: Dec 31, 2025

   Abstract PDF

  The present study aimed to investigate the effects of dietary supplementation of peptidoglycan, Lactobacillus plantarum, or their combination on the growth performance, disease resistance, and immune status of juvenile striped catfish. Fish were fed on a commercial feed supplemented with various concentrations of peptidoglycan (PG5.0: 5.0g per kg of feed), Lactobacillus plantarum (PL5.0: 5.0g per kg of feed), or the combination of the two (PP0.0: 0.0g + 0.0g per kg of feed; PP2.5: 2.5g + 2.5g per kg of feed); PP5.0: 5.0g + 5.0g per kg of feed). Fish were then fed at a rate of 3% of their body weight for six weeks. After the feeding trial, fish were infected with Aeromonas veronii at 50% the lethal dose (LD50, 107 CFU/mL). Blood samples were collected after two, four, and six weeks of the experiment and on the second day after bacterial infection for hematological parameters and immune assays. The results demonstrated that supplementation with PP2.5 significantly improved the growth performance and feed utilization in fish, while the LP5.0-based diet reduced mortality in A. veronii-challenged fish, indicating enhanced disease resistance. The modifications in hematology and immune status were affected by the pro-, pre-, and synbiotics tested in this study. In conclusion, dietary supplementation with peptidoglycan and L. plantarum enhances growth, immunity, and disease resistance in striped catfish, supporting sustainable aquaculture practices for improved fish health and production efficiency, with the optimal ratio being 2.5g peptidoglycan + 2.5g L. plantarum or 5g L. plantarum per kg of diet in striped catfish.

• The Role of Fish Markets in Organizing Coastal Community Livelihoods: A Case Study of Giao Hai, Nam Dinh, Vietnam

  Nguyen Thi Minh Khue, Nguyen Thi Dien, Pham Thi Thu Ha, Nguyen Truong Xuan, Philippe Lebailly

  Received: Aug 21, 2025 / Accepted: Dec 12, 2025 / Published: Dec 31, 2025

   Abstract PDF

  This study analyzes the role of the Giao Hai fish market (Giao Thuy district, Nam Dinh province) in organizing and sustaining coastal community livelihoods. By integrating perspectives from small-scale fisheries, trader–fisher relations, gender analysis, and local ecological knowledge, the research is based on 27 in-depth interviews and participant observation conducted between March and June 2025. The findings reveal that the Giao Hai fish market functions as a strategic hub linking harvesting, trading, and processing, largely governed by informal institutions and community social capital. Relations between traders and fishers simultaneously provide essential financial and logistical resources but simultaneously create asymmetric dependencies. The gendered division of labor ensures the continuity of the supply chain but also reproduces inequalities in economic power. Current challenges include declining fishery resources, price volatility, competition from non-local traders, and limited cold storage infrastructure. The study recommends a combination of socio-economic measures and resource management strategies to secure sustainable livelihoods while protecting and restoring marine resources.  

• Effects of Dietary Gamnui (Gnetum montanum) Extract on Growth Performance, Immune Response, and Disease Resistance in Juvenile Striped Catfish (Pangasianodon hypophthalmus)

  Le Xuan Chinh, Nguyen Thu Hang, Nguyen Thi Mai

  Received: Jul 04, 2025 / Accepted: Dec 08, 2025 / Published: Dec 31, 2025

   Abstract PDF

  The present study investigated the effects of dietary supplementation with Gamnui (Gnetum montanum) extract on growth performance, immune response, and disease resistance in striped catfish (Pangasianodon hypophthalmus). Four experimental diets were formulated by adding Gamnui extract at 0 (G0), 2 (G2), 5 (G5), and 10 g kg-1 feed (G10), and administered to juvenile fish for six weeks. Growth parameters including final weight, weight gain, daily weight gain (DWG), specific growth rate (SGR), and feed conversion ratio (FCR) were recorded, along with relative internal organ indices. Post-feeding, fish were challenged with Aeromonas veronii to assess cumulative mortality and immune-related parameters. The results indicated no significant differences among dietary treatments in terms of final weight, weight gain, specific growth rate, or feed conversion ratio. Similarly, hepatosomatic (HSI), viscerosomatic (VSI), and gut indices (GSI) were unaffected. After bacterial challenge, the G10 group exhibited the lowest cumulative mortality, compared to the control (G0). Dietary Gamnui extract modulated several immune-related indicators: myeloperoxidase (MPO) activity increased consistently in fish receiving 10 g kg-1, while glutathione (GSH) levels were elevated across all supplemented groups, indicating enhanced antioxidant capacity. Peroxidase activity exhibited a treatment-dependent response after infection, whereas lysozyme activity did not change.. In summary, dietary Gamnui extract did not influence fish growth performance but enhanced non-specific immune responses and disease resistance, particularly at 10 g kg-1. These findings highlight the potential of this medicinal plant extract as a sustainable immunostimulant in aquafeed for striped catfish.