I AM SO IN.
Gonna try for a p/t colorist position too heart
Crazy colors and patterns, YES YES YES (thinking jaguar-and-white-cambodian-style crowntail here XD)
Accessories for tanks would be great. I'm thinking if you do aquarium-setting most of the rp will be between the owners, but that's okay! There are a lot of opportunities there!
I don't know about, say, clothing edits, but some edits like ragged fins or something like that would be cool to have show up once in a while.