If fish where killed by water

So some normal fish were swimming thern they started melting so they tried to get out then they all got out and said we need a new home so they took the sky and all the human race died of  tactual nuke and the fish took over the world except for Korea cause they have lot of weapons.then they said we have to move they're are to many fish so then the other guy said let's move to the oceans like in bio shock. So they did and life was good.