Probiotic Efficacy Test to Improve Fish Health and Growth!

Getting to Know Probiotics More Deeply

Probiotics are live microorganisms that provide health benefits when consumed in appropriate amounts. Currently, probiotics are becoming increasingly popular and widely used by the aquaculture sector as a strategy to improve health, enhance growth, and reduce the risk of disease in fish.

The use of probiotics is not limited to feed but can also be applied as water additives, where probiotics are introduced directly into the ponds to improve water quality and fish health. Research shows that around 20 genera of bacteria have been identified as probiotic candidates, with Bacillus spp. and Lactobacillus spp. being the most promising species.

Testing Methods for Fish Probiotics

To date, many producers have started manufacturing probiotics to meet consumer demand, with products generally available on the market in tablet or liquid form. To ensure the quality of a probiotic product, efficacy testing is crucial. This testing provides assurance to consumers that the microorganisms contained in the product are safe and effective for use. Additionally, this testing can determine the optimal dosage and appropriate formulation for specific fish species, ultimately enhancing productivity and profitability for producers.

One of the efficacy tests commonly performed is in vitro testing to evaluate the ability of probiotics to inhibit the growth of pathogens affecting fish health. This test involves observing the interactions between probiotics and pathogenic microorganisms in microbial cultures, as well as measuring parameters such as cell viability and beneficial metabolite production. One method that can be used in this testing is antagonism testing, where the probiotic is evaluated for its ability to inhibit the growth of pathogenic bacteria by observing inhibition zones or the reduction in the number of pathogenic colonies in culture. Antagonism testing is an effective way to assess the potential of probiotics in aquaculture applications, particularly in controlling pathogenic infections and enhancing fish health.

Several pathogens commonly found in aquaculture systems can cause significant losses in fish production, including Aeromonas hydrophila, which can cause aeromoniasis and often results in mortality in cultured fish; Vibrio spp., including Vibrio harveyi and Vibrio anguillarum, which are known to cause serious infections in various fish species, especially in aquaculture environments; and Streptococcus iniae, which can cause streptococcal infections in freshwater and some marine fish.

The first step in this test is to prepare viable cultures of pathogenic microorganisms and probiotics. Next, suitable growth media, such as Nutrition Agar (NA) or MRS agar, are prepared, depending on the type of microorganisms being tested. After that, inoculation is carried out by spreading the probiotic culture on one side of the agar, followed by inoculating the pathogenic bacteria on the opposite side. The agar is then incubated at an appropriate temperature for 24-48 hours to ensure the growth of both microorganisms.