Primavera otoño 2020 (Año LXIII Núms. 122-123) Año LXIV Núm. 124-125 horizontes PRIMAVERA / OTOÑO 2021 PUCPR 54 PROBIOTICS IN AQUACULTURE: AN ALTERNATIVE FOR A HEALTHY AND PROFICIENT SHRIMP FARM José C. Álvarez Martínez Pontifical Catholic University of Puerto Rico Biotechnology Master’s Degree Program Abstract Aquaculture requires new technologies for massive and healthy production of the Penaeus monodon and Litopenaesu vannamei species, which are in high demand in shrimp farms. Biotechnology contributes to manipulating terrestrial microorganisms in food probiotics for the use of aquatic animals. In previous years antibiotics were used to eliminate the most common diseases in hatcheries. Still, new advances have shown that they create bacterial resistance and concern the consumer community. Probiotics provide a natural alternative to fight against most of the diseases in shrimp farms. Probiotics improve the shrimps' immune system, allowing them to fight infections with their defense system. Also, the constant use of probiotics in hatcheries helps the shrimp to develop faster and healthier. In these farms, shrimps will have more diverse gastrointestinal microflora, allowing them to have more chances of survival. The use of probiotics affects shrimps internally and externally, contributing to a healthier, naturalist, and toxin-free hatchery. Introduction Shrimp farms increase the consumer population's nutritional value and contribute to the global economy (Babu et al., 2021). Despite being a profitable business, these shrimp farms have been affected by pathogenic microorganisms that eliminate dozens of hatcheries, creating significant economic losses (Ahmmed et al., 2018). To avoid these losses, experts in the field have developed various techniques using probiotics to replace the traditional use of antibiotics to prevent pathogenic mutations (Ahmmed et al., 2018). Huerta-Rábago et al. (2019) define probiotics as living organisms administered in adequate doses confer health benefits to the host. Aquatic environments have various stressors such as pond density, temperature, salinity, anoxia, hypoxia, hyperoxia, chemicals, pesticides, and pathogens. These stressors create various shrimp diseases such as necrosis and vibrosis, affecting the development of the product. Bacteria of the genus Vibrio are part of shrimp's natural microflora. These bacteria are opportunistic organisms, especially when there is a microbial imbalance within shrimp intestines. Once pathogenic bacteria take over, they create biochemical inhibitions, substrate competition, and nutrient competition against the shrimp's natural flora (Arias-Moscoso et al., 2018). It is not adequate to use antibiotics against shrimp's pathogens because pathogenic bacterias could create resistance, especially to erythromycin and ampicillin antibiotics (Babu et al., 2021). Adding probiotics to the water, the survival of the shrimp or species of interest increases; environmental stressors decrease and the species' immune system increases, improving the hatcheries' production (Dawood et al., 2019). Kewcharoen and Srisapoome (2019) showed that in five weeks of moderate use of probiotics in shrimp feed, their size and weight increased faster than shrimp without probiotics. In addition, they proved that the immune system was improved due to the increased activity of phagocytes in the organism. According to the research by Dawood et al. (2019), the microbiota-host relationship is crucial for the host's survival. The microflora carries out processes that the host organism