yes, and Im suggesting that your emphasis on their racial characterization is on the 'fish", not the human(oid) aspect, and are defining how they should be by what you consider fish to have. This doesnt even address that fish is short hand, or that not everything that lives in rivers and oceans are 'fish', so they could be more closely related to mammalia and we wouldnt know (after all we literally have things like platypus, whales, sea lions, and other creatures on earth here who dont quite fit into the basic characteristics we describe).
Youre doing the same thing as the creatives, just from 'the other direction'. A brood mother should be like x and y, cause real world and simplification of a concept.
It's not unknown what I put in the spoiler texts. It specifies one species in particular but the quest plotline implies most (if not all) of them are under the same condition.
You can pretty much break down everything to a 'design' short cut depending on how you classify it. Want to quickly establish a character is threatening or menacing - give them spiking or pointed armor or clothing that evokes such.
You want to quickly establish a female, well, in human terms, things like breasts do it quickly particularly on humanoids. Furthermore, you actually dont know what the biology is or how they function reproductively. What little we know has been extremely simplistic and describe in quick terms to get a basic point across. We didnt sit down and have a lesson on "This is the reproductive and mating procedures of sagahagin."
In fact, going back to my initial point - the fact that you consider a horrific brood chamber to be the hallmarks of a 'fish mom' is how you personally interpret how it should look, which is a subjective thing. Fish reproduce in a variety of ways, and having some horrific chamber filled with nothing but eggs like a kind of hive is what you think ti should be like. How do you know it wouldnt have neetly deposited eggs, or what those eggs would even look like, or instead of eggs in piles, you have spawning pools that are hidden from view. Perhaps eggs are depositied underwater so you wouldnt even see them at all.
But the thing you did was went to fish boobs. To give you another perspective, albeit anecdotal, I literally didnt realize she had breasts until a month ago, and Ive been doing that in roulettes since it came out. I never noticed it on the design, and knew she was female because we were told so in character dialogue, which short of knowing the exact anatomy of a species or relying on short hands, is pretty much best you can ask for.
Its a matter of preference and perspective in regards to this. design choices you either do or dont approve of. An antichamber filled with oozing eggs and something out of a horror movie is cliche to me. It would get your point across, sure, but its also been done to death.