Improvement Suggestions !!!

Question

Can anyone suggest some improvements in animations in my code.
I feel it's lagging on phone. Also, if i execute init method for random fish movements, it becomes worse.
Any help or suggestions would be appreciated. Thanks.
https://code.sololearn.com/Wjl5i2D1YANu/?ref=app

Answer 1

More bubles, smaler bubles, and fish could change dimensions to give a 3d inpression.
It is nice, well done.

Answer 2

Thanks @Emore for the feedback. Will be working on Making it more real and 3D kind.