>>533988078
>>533988783
>>533989726
I still haven't actually gotten to it myself so I'll see if I can determine anything more specific, but from my understanding of the other Monster Girls (like how Ghosts are not actually born from eggs shaped like gravestones, they really are just ghosts, it's just most don't have memories of their former lives so Ameri genuinely did believe that), I think because Oxy can talk to fish and other sea-life, she was adopted and raised by two foster parents who took her in and has come to view them as truly her own flesh-and-blood family, and it just so happens that her adoptive parents are actual literal fish. Regardless of the case, she believes that as a Mermaid, fish are the same kind as her, and she views all fish as her people.
Perili is aware that fish are not identical to Mermaids however so she doesn't understand the issue because she doesn't want to eat Mermaids and she has to eat fish or she'll starve.
And also because she just likes fishing, and Oxy will attack her even on days she's just trying to enjoy herself with some simple catch-and-release.
>>533988078
which leads me to what's most important here:
the thing is that Oxy is exactly as deranged as Perili is, right down to how both of them even try to hide their real manner of speaking in order to appear more cute.
When Oxy drops the act her voice tone completely shifts, becomes much deeper and she starts acting like she's a member of a fucking mafia or cartel group. She's also extremely violent about no one eating fish; Oxy doesn't just view all fish and mermaids as one and the same she's distasteful towards ANYTHING that eats fish, even other sealife, and yet she's also selective about it because she actually likes bonito flakes (i.e, very processed fish).
When both of these things get pointed out to her, both times she ignores it but in the latter case it's probably because she didn't know and doesn't want to accept it.