Which factor allows bacteria species to adapt to environmental changes faster than fish?

There are a few things that allow bacteria to evolve fast and thus, to adapt to new environments:
·     short generation time-which means that their reproduction occurs very quickly (sometimes only few minutes)
·     random mutations-mutation rates are high in bacteria, resulting structural changes cha or for example, loss in sensitivity to antibiotics
·     genetic recombination-mechanisms which occur during the DNA transfer (transformation, transduction, conjugation).