Big Fish is a terrible game.
There's nothing wrong with the premise; I love Fishy, for instance, which is a very similar game in terms of the basics, with classic gameplay and concepts.
Big Fish tries to mess with the formula. It gives you missions. The mission in the above? Protect the little red fish, which are your "babies."
If you touch your babies, you eat them. (And the controls are junk.)
THIS IS STUPID.
So my recommendation on this game is... play Fishy instead. There you get to be an ecosystem-wrecking eldritch abomination instead of eating your own babies by accident because your fish is difficult to control.