Fix jitter in fish movement

[maddiedierker]

Fish appear to jump forward due to frame dropping, which is caused (at least in part) by our tinting code (here), so we should refactor how we're tinting fish.

We think there are other expensive operations contributing to frame dropping, but tinting seems to be the biggest culprit, so we should tackle it first.

This StackOverflow article may help provide good alternatives.

[Tunki1201]

Dear AI ocean team,
I am so interested in your project.
I saw your job position in upwork, but you sent an invite, that's why I make a comment here.
😢

Could you give me a chance to work with your team?