Thanks! It was cool to see somebody else checking it out. You actually didn't encounter the severe bug that ruined the whole thing =P
If you had yourself been eaten, which happens a lot, it would have bugged out, and you'd have been an invisible fish swimming around with a ghost fish attached to you. It didn't make it into the instructions, but one of the things that mutates (invisibly) is your size. Fish can only eat fish smaller than themselves (unless they're as small as they get, in which case they eat fish their own size.) The trick is this: if you're bigger than your mate, you have to get smaller, so getting eaten makes you smaller! (Unless you're already small, in which case it's game over.)
This makes it kind of a rotating process, where you have to manage the acquisition of attributes against the fact that you'll also have to manage your size. Shame it all bugged out before the deadline, but it'll get bugfixes *apart* from the jam.