The game itself play alright, but it's just really... boring and not that fun. There isn't any real motivation to keep playing multiple levels. After winning about the first five I really got bored and couldn't keep going.
The background and art work is nice, but there were some things that need to be improved on. The green sides of the background were really out of place. I don't recommend that their there and it would have been much better if you just kept the water background across the entirety of the back screen.
Also, some of the fish just swim to the end of the screen and just disappear. They should swim off of the screen to make things more fluid. At the end of the day, other than the fish theme this really really has nothing to do with dolphins and/or fish and it's a huge stretch. I would have worked out a better theme for this game.
Like your other game, there is no restart button. Not that I needed one because of the simplicity and ease of the game, but I let this play while writing a review and realized that if someone does lose they have to refresh the entire screen to play again.
The audio was alright, but needs to be toned down and their needs to be some ambient background music to go along with everything.