Simão Zacarias

Live transport is a critical component of fish hatchery and nursery operations, particularly when larvae are transferred from hatcheries to nursery facilities. This study evaluated the effects of larval age at transport (24, 48, and 96 hours post-hatch), transport duration (3, 5, 7, and 10 hours), and oxygen management on the post-transport survival and subsequent nursery performance of Pangasius catfish. Three complementary experiments were conducted. In Experiment 1, larvae transported at earlier developmental stages (24–48 hours post-hatch) and for shorter durations (3–5 hours) exhibited significantly higher immediate post-transport survival. In Experiment 2, survival after 10 days of nursery rearing in hapa nets ranged from 12.4% to 23.9% among treatments. These values were 1.5–2.0 times higher than survival rates commonly reported by nursery farmers at 1–2 weeks after transport. Experiment 3 evaluated longer-term survival after 25 days of nursery rearing and confirmed the strong effects of both larval age and transport duration. The research also found that without oxygen replenishment, the highest survival rate (49.7 ± 4.7%) was achieved when larvae were transported within 24 hours post-hatch for no longer than 3 h, whilst oxygen replenishment at 3h intervals further increased survival to 55.3 ± 7.8%. Overall, transporting larvae at an early developmental stage, minimizing transport duration, and maintaining adequate oxygen levels substantially improved post-transport survival and subsequent nursery performance. These practices may therefore enhance production efficiency and fish welfare in Pangasius catfish aquaculture production.

This study investigated the perceptions of AAW among educators (n = 47), students (n = 359), and aquaculture sector stakeholders (n = 34) in key aquaculture regions of South and South-Central Vietnam. Using a mixed-methods survey, perception scores, understanding of core welfare concepts, curricular coverage, and willingness to pay (WTP) for higher-welfare products were assessed. Although perception scores were high across surveyed groups, only 5.57% of students identified most of the Five Freedoms of Animal Welfare, while 17.0% showed no understanding of welfare. This highlighted a gap between awareness and understanding, leading to the development of the Awareness Depth Gap Framework. A small but statistically significant negative correlation (Kendall–Theil –Sen slope = −0.28, p < 1.25 × 10⁻¹²) indicated that greater AAW curricular inclusion was associated with stronger welfare attitudes. Willingness to pay modest premiums (6–10%) for higher-welfare products increased non-linearly with higher perception scores among educators and students. In contrast, aquaculture sector stakeholders appeared to prioritise economic factors over welfare. These results highlight the need for structured AAW curricula and community collaborative education to close knowledge gaps. This study provides the first empirical insights into AAW perceptions across the education and aquaculture sectors in Vietnam.

This study was carried out to investigate the perceptions of aquatic animal welfare (AAW) among educators (n = 47), students (n = 359), and aquaculture sector stakeholders (n = 34) in key aquaculture regions of South and South-Central Vietnam. Using a mixed-methods survey, we assessed perception scores, understanding of core welfare concepts, curricular coverage, and willingness to pay for welfare-friendly products. Although perception scores were high across surveyed groups, only 5.57% of students could identify most of the Five Freedoms of Animal Welfare, and 17.0% showed no understanding of welfare, highlighting a gap between awareness and understanding. No significant differences were found by academic major or year, indicating systemic curricular gaps. A small but significant negative correlation (Kendall–Theil Sen slope = –0.28, p < 1.25 × 10⁻¹²) suggests that greater curricular integration of AAW is associated with stronger welfare attitudes. Willingness to pay modest premiums (6–10%) for welfare-friendly products increased non-linearly with higher perception scores among educators and students, while aquaculture sector stakeholders appeared to prioritise economic factors over welfare. Although 88.2% of aquaculture sector stakeholder’s respondents supported curriculum reform and practical training opportunities, few (41.2%) identified formal competency standards for graduates. These results highlight the need for structured AAW curricula, community collaborative education models, and targeted interventions to close awareness understanding gaps. This study provides the first empirical insights into AAW perceptions among key education and aquaculture industry groups in Vietnam, offering a foun-dation for policy-driven curriculum reform to support ethical and sustainable aquaculture.

Effect of K⁺ and Mg²⁺ in water on the performance of Litopenaeus vannamei using bioflocs was evaluated. Control had water with K:Mg (1:4.57) and other treatments (K:Mg of 1:5.4, 1:4.65, and 1:3.77), both with salinity of 4 g/L. Initial mean weight of shrimp was 0.08 ± 0.007 g. No difference in shrimp growth performance and survival was observed (P > 0.05) except in the control. Our results suggest that it is possible to culture postlarvae of Litopenaeus vannamei in low-salinity water with bioflocs when the water has an initial potassium concentration of 30.90 ± 8.5 mg/L and magnesium of 167.0 ± 3.9 mg/L.