HELLO ANON I KNOW ABSOLUTELY NOTHING ABOUT FISH BUT IM SO READY TO ANSWER THIS!
yingxing: clownfish. so then he can act really excited, grab jing yuan, and go in a really deadpan voice; "this is you if you were a fish."
jingliu: betta fish. pretty.
dan feng: koi. pretty.
baiheng: any form of edible fish. anything is edible if youre hungry enough on some freezing planet (and if youre a yaoqing citizen. she was ABSOLUTELY banned from rainsoar lake in her day)
jing yuan: knowing his love for rare animals, i bet it's some crazy rare fish that nobody has heard of