World Aquaculture - March 2023

52 MARCH 2023 • WORLD AQUACULTURE • WWW.WAS.ORG of torn fins and missing eyes than no-probiotic controls. From these results, a Condition Index (CI) was developed for red drum that may be useful to farmers in determining red drum health and condition. This is especially important for a species like red drum that is sold whole to buyers because fish showing no wounding or torn fins improves profitability. Although PrimaLac® improved growth and condition in red drum, there still remains the question: how do PrimaLac® probiotics produce improvements in red drum growth and condition? Histological sections from red drum intestines showed PrimaLac® increased functionality in the gut by reshaping and improving the health of the digestive tract compared to controls (Busby 2021). From 16s sequencing of the gut microbiota of red drum intestines, gut microbial diversity of PrimaLac®-treated fish (Fig. 3B) was greater than that of control fish (Fig. 3A). Further, increased microbial diversity, in conjunction with increased intestinal morphological complexity, may have contributed to positive physiological changes, such as decreases in the stress markers of blood glucose and lactate (Busby 2021). Together, these results suggest that PrimaLac® probiotics aided in countering stress-related (acute and chronic) effects common in fish farms, thus significantly improving fish welfare and productivity. Conclusions Microbial diversity of the gut promotes strength. Aquatic animal health is intrinsically linked to the natural microbial populations of the intestines. Application of 16s sequencing technology makes it possible to detect microbes that cannot be grown in culture, increasing awareness of the immense importance of microbial populations to organisms’ health and well-being. It is important to consider probiotics dosage levels, as well as the numbers and types of bacteria present in the probiotic and how they interact with hostresident bacteria. With increased knowledge about the importance of microbes to fish welfare, we may be able to achieve truly sustainable aquaculture, one that will withstand the challenges of increased stressors associated with farming practices, as well as increasing changes in future, climate-based stressors. This integrative approach to stress management offers an alternative to the use of antibiotics and helps ensure a sustainable and safe seafood supply. Acknowledgements Our gratitude to Jim Ekstrom, CEO, Ekstrom Enterprises and David Maus, Co-owner and Director of Copper Shoals Red Drum®, Ekstrom Aquaculture LLC, Palacios, TX for providing the red drum juveniles and for the all the help and information. Our thanks also to Bob Adams (CFO) and Dr. Young (CEO), of Star Labs (manufacturer of PrimaLac®) for providing PrimaLac®, and for all the infrastructure support. Rangen Inc. aided in feed formulation. This work was supported by generous funding from Lone Star Labs #1600208-70003 as well as an UNT internal grant to IHvH. Notes Ione Hunt von Herbing, Wren Busby, Michael Anderson, and Victoria Youngblood, UNT Marine Conservation and Aquatic Physiology, Department of Biological Sciences, University of North Texas. Denton, TX 76203. Bailu Zhang, Department of Computer Science and Engineering, University of North Texas. Denton, TX 76203. Corresponding author email: vonherbing@unt.edu References Anderson, M.E. 2019. The effects of probiotics on growth and metabolism in juvenile Oreochromis mossambicus (Mozambique tilapia). M.S. Thesis, University of North Texas, May 2019. Avella, M.A., I. Olivotto, S. Silvi, A.R. Place and O. Carnevali. 2010. 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