Abstract

Mass scale culture of marine ornamental fish is facing many problems caused by pathogenic microorganisms. The accumulation of unconsumed feed and bad water quality influence the growth of pathogenic forms of the Vibrio sp. To avoid these problems probiotics are used as an alternative agent in vitro for efficacy based on the inhibition of growth of pathogenic Vibrio sp and also it decreased the concentrations of ammonium, nitrite, nitrate and phosphate ions.  The present study revealed that after the use of probiotics in experimental tank the beneficial microbial load is drastically increased but decreased the level of pathogenic Vibrios. The bacterial population changed during every sampling. THB in the experimental tank before the application of probiotics ranged from 2.39 x 10³ to 4.82 x 10⁴. After the application of probiotics, THB population varied between 4.21x 10⁶ and 7.43 x 10⁷. In the control tank, THB count was found to be between 5.28x 10³ and 2.1 x 10⁵, but Vibrio load was high. Vibrio sp counts ranged from 6.82 x10² to 9.21 x 10³ CFU/ml in the experimental tank prior to application of probiotics. After the application of probiotics, Vibrio population varied between 1.62 X10² and 3.96 x 10² CFU/ml. In the control tank, Vibrio count was found to be between 8.56 x10² and 2.1 x 10⁴ CFU/ml.

Key words: Probiotics, ornamental fish, disease.