You've finally got a fix for "Hey you can beat this villain by just staying out of the water" and then they barely ever use it. Sure, it makes no sense that the piranha can fly, but seeing as they can, you may as well have used that ability to the max. But 99% of the victims are still water-bound. Whatever, it's a modicum of fun in that dated practical effects way.
Final rating:★★ - Had some things that appeal to me, but a poor finished product.