Cute simple game, lacking some critical feedback to your actions.
-My favorite part is the round trip, that let you make a second attempt at become friends with fish you missed the first time. And the nice general theme, just making some fish friends.
-When I finished the first level, I was like 'it would be good if you needed to hit some fish multiple times to become friends' and then hey, that's exactly what the second level required.
But just the 2 different sounds, ended up making it initially sound like there were also some fish that couldn't become your friends. Instead of being required to hit them multiple times. If a gray heart popped up above them each time, and then when there were enough of them it transformed into the one red heart indicating they were your friends, that would help a lot.
Also the moment they become friends could be made more impactful, like with a simple particle system shooting out a few hearts in random directions.
It may betray the simplicity/current game type, but because for example the crabs could end up hiding under some fish and not be accessible, it would create some more engagement if you could aim the love bomb being sent out by pointing with your mouse.