Basically, Fishmen are humanoids with aquatic features (fins, scales for skin, weirdly tinted skin, sharp teeth, tails etc. and sometimes have adapted senses and the like) and they Do Not Like Humans and vice versa.
Lol, I'm 5' 3" or 4". This YouTuber I watch is supposedly four foot something, but I really can't believe that. Maybe they said five foot. I swear she or someone else said four foot something though.