I can tell you what to improve on! Well, hmm, make the audio volume equal, either all soft, or all loud, to prevent unintentional ear rapes to headphone users like myself, practice transitions and add a little more details to your drawings, plus...PRACTICE! Practice makes the good animator!

The audio is very quiet except for the door and screeching-violin sound effects, the latter is way too loud.

Everyone already knows this about certain fish soooo entertainment value is gone, especially with no fighting scene between "fighting" fish. Animation isn't the worst.

Not bad for your first flash animation. Given that it was a beta fish, the plot itself was rather predictable. That said, this was a valiant first effort.