Question

why is meiosis needed in his fishes which reproduce sexually​

Answer 1

Answer:

Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes (including single-celled organisms) that reproduce sexually.

A few eukaryotes, notably the Bdelloid rotifers, have lost the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis.

Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as mitosis or binary fission.