author(s)
Sakshi Sharma, Tejpal Dahiya, Monika Jangra, Abhimanyu Muwal and Chandan Singh

abstract
Probiotics (originated from the Greek words pro and bios, which means for life) are beneficial microorganisms and their products, having the beneficial effects on the host. It is being recently used in aquaculture to control diseases and also treated as supplements for improving growth and in some cases as a means of replacing antimicrobial compounds. Besides, enhancing growth performance and improving haematological parameters of fishes, it also improves water quality which is considered as most important for freshwater fish habitat as fishes are extremely sensitive to changes in environmental factors viz., temperature, water salinity, oxygen level etc. Thus, this review summarizes current studies regarding the effects of probiotics on growth performance, haematological parameters of various fishes and water quality.