It is a kind of for increasing the weight and growth rate of fish, the preferably method of salmonidae, for preventing and/or handling microbial diseases, the following steps are included: a) one or more types of addition probiotic bacteria are to water, wherein the type of bacterium includes or is made of Aliivibrio njordis, Aliivibrio balderis and/or Aliivibrio wet nurse； B) aqueous one or more types of the exposure fish to probiotic bacteria. Preferably, bacterium bacterial strain Aliivibrio njordisstrain Bl-25,8-1/2013 mandib Vll, Aliivibrio balderisBl-24,18-1/2013 kidn V12 and/or Aliivibrio nannieB8-24,313/2013 kidn V13 use.The present document is directed to probiotic bacteria and their use in fish farming for increasing the weight of fish and for treating and/or preventing a microbial infection of the fish. The bacteria are three novel species within the Aliivibrio genus.
