Actually the original design I had in mind was for Goldfish. Turn them into torpedo boats. But Fish viability is already there. However, if you want it returned to being like it was in 1.1 then it is simple. Just remove the arming timer on heavy flak along with the nerfs it had to dmg. Back then you didn't see carronade fish or really any other type aside from Hwatcha because Flakfish were so good at delivering high blasts of dmg at varied ranges.