World Aquaculture - December 2023

14 DECEMBER 2023 • WORLD AQUACULTURE • WWW.WAS.ORG • Vera, L., Aguilar Galarza, B., Reinoso, S., BohorquezCruz, M., Sonnenholzner, S., & Argüello-Guevara, W. (2023). Determination of acute toxicity of unionized ammonia in juvenile longfin yellowtail (Seriola rivoliana). Journal of the World Aquaculture Society, 54(5), 1110–1120. Available at: This study provides an important assessment of unionized ammonia (NH3-N) and total ammonia nitrogen (TAN) toxicity for juvenile longfin yellowtail, Seriola rivoliana. The authors assessed the median lethal concentration (LC50) after a 96 h exposure of triplicate groups of fish to different ammonia concentrations: 0.55 ± 0.00; 0.94 ± 0.02; 1.18 ± 0.00; 1.72 ± 0.02, and 1.97 ± 0.09 NH3-Nmg/L. A control group (0.00±0.00 NH3-Nmg/L) was also included and the 96h LC50 for unionized ammonia was found to be 0.58mg/L for S. rivoliana. Clinical toxicity was evident in fish exposed to different concentrations and appeared as specific lesions on gill tissues; characterized by hyperplasia, epithelial lifting, and secondary lamellae fusion. Irreversable damage was evident along with erratic behavioral signs that included swimming in circles and hyperventilation. The goal of this study was to provide a first-hand evaluation of the effects of unionized ammonia on S. rivoliana and establish parameters for proper water quality management. The findings suggest that a concentration that does not exceed 0.06mg/L or 1.68mg/L for unionized ammonia or TAN, respectively, is safe for rearing juvenile S. rivoliana at a salinity of 32g/L, pH8, and 25°C water temperature. This study provides valuable baseline water quality data for this marine species and will be important for intensive and semi-intensive culture of S. rivoliana. • Pham Thi, H. H., Kim, D.-H., Quach Van, C. T., Nguyen, P. T., & Nguyen, T. L. (2023). Prevalence and antibiotic resistance the Journal of the World Aquaculture Society Editor’s Choice Awards 54(5) of Aeromonas schubertii causing internal white spot disease on snakehead fish, Channa striata, in the Mekong Delta, Vietnam. Journal of the World Aquaculture Society, 54(5), 1260–1276. Available at: Snakehead, Channa striata, are a high-value and popular aquaculture species but have had a long history of invasion in the Mekong Delta and other regions of the world resulting in negative impacts on native aquatic species biodiversity. A bacterial disease known as internal white spot disease caused by Aeromonas schubertii is a major problem in the production of snakehead. This study was aimed at characterizing the prevalence of antibiotic resistance in bacterial isolates collected from farms in the Mekong Delta region due to the potential public health concern should multiantibiotic resistant (MAR) bacteria spread to wild populations or to consumers. Isolates were collected from white nodules in affected fish and identified based on morphological and biochemical tests, combined with an analysis of housekeeping genes (16S rRNA, gyrB, and rpoD). Disease causing isolates were strongly identified as A. schubertii, and it was found that all isolates (n = 25) were phenotypically multidrug-resistant, with resistance to erythromycin (84%), rifampicin (84%), flumequine (88%), amoxicillin (96%), ciprofloxacin (92%), and florfenicol (92%). The MAR indices ranged from 0.33 to 0.92, with one isolate of A. schubertii showing resistance to 11 of the 12 antibiotics tested. Further hierarchical clustering analysis of antibiotic-resistant bacteria suggested the potential to spread between ponds/fish farms and the ability for bacteria to survive for up to 3 months in aquatic environments. These results suggest that the diversity of MAR A. schubertii in snakehead represents a potential risk to native aquatic organisms and consumers, and emphasize the need for judicious use of antibiotics in aquaculture to limit the development of MAR bacterial species. Table of Contents Journal of the World Aquaculture Society 54(5) Your society journal JWAS is fully available to you including all back issues at or at (just click on the photo of JWAS). Editorial Villarreal,H. (2023) Shrimp farming advances, challenges, and opportunities, 54(5), 1092–1095. Applied Studies Buchalla, Y., McGuigan, C. J., Stieglitz, J. D., Hoenig, R. H., Tudela, C. E., Darville, K. G., Ibarra-Castro, L., & Benetti, D. (2023). Advancements in hatchery production of red snapper Lutjanus campechanus: Exclusive use of small strain rotifers as initial prey for larval rearing. Journal of the World Aquaculture Society, 54(5), 1096–1109. * Vera, L., Aguilar Galarza, B., Reinoso, S., Bohorquez-Cruz, M., Sonnenholzner, S., & Argüello-Guevara, W. (2023). Determination of acute toxicity of unionized ammonia in juvenile longfin yellowtail (Seriola rivoliana). Journal of the World Aquaculture Society, 54(5), 1110–1120. jwas.12971 Zaman, M. F. U., & Cho, S. H. (2023). Dietary inclusion effect of various sources of phyto-additives on growth, feed utilization, body composition, and plasma chemistry of olive flounder (Paralichthys olivaceus), and challenge test against Edwardsiella tarda compared to a commercial probiotic (super lacto®). Journal of the World Aquaculture Society, 54(5), 1121–1136. https://doi. org/10.1111/jwas.12978 Kim, J., & Cho, S. H. (2023). Inclusion effect of jack mackerel, Trachurus japonicus, meal in the diet of rockfish, Sebastes schlegeli, on growth, feed utilization, biochemical composition, and innate immune responses. Journal of the World Aquaculture Society, 54(5), 1137–1161. Chen, Z., Ibrahim, U. B., Yu, A., Wang, L., & Wang, Y. (2023). Dried porcine soluble benefits to increase fish meal replacement with soy protein concentrate in large yellow croaker Larimichthys