I really like the idea that the player tries to catch the main fish using enemy fish that all have different mechanics or behaviors. I think the AI of the main fish creates a good level of difficulty and I like the game's music.
My two main issues are 1. The enemy fish don't have enough unique or interesting mechanics to make gameplay fun. The blowfish mechanic is fun, useful, and flavorful. None of the others really stand out 2. The enemy fish don't feel reactive enough. They react so slowly I don't really feel in control of them. So my main strategy becomes just waiting for a situation where a useful fish comes close enough to be useful. And waiting isn't fun.