If you don't understand the comparison between Bio-Trophies (who can only live in preserve buildings) and Aquatics (who can only live in oceanic developments), then there's not much room for discussion between us.So because some other, completely unrelated feature doesn't exist this one can't either?
That's ridiculous.
Enjoy your games.
What's ridiculous is the idea that Tiles had no place for aquatic species, but the current UI does have a place. It's just too backwards to be taken seriously.This isn't so ridiculous as an idea. Right now, every planet has uncapped housing districts (and thus building slots can always be maxed, provided its over a certain size, given certain techs that give extra slots).
It might well be interesting if cities were capped [cap shared with industrial districts?], much like farms, they would be dictated by planet deposits (e.g. "stable ground" "river delta" or whatever. which give +X cities districts). Whilst Oceanic worlds could give +Y "Oceanic City Districts" - However this would require a re-work on how housing works [debatably, needed anyway, given the introduction of carry capacity] if you wanted fish people vs land people (so X/Y land housing, J/K fish housing etc). So for this specifically it might not be a great idea, given time vs payoff ("impact analysis").
But I think there could be some interesting things coming out of capping city districts, too. At least, it could lead to a few more useful Soc techs (something like unlock Dry/Wet/Cold/Tomb city development, opening more housing up in the midgame), and a few less cookie cutter planets (if cities are capped, building slots are rarer, and you cant always carpet them in labs... which probably ought to be rolled in to cities somehow, or a planetary tech district anyway tbf).
Now, you could create a new UI which did have a way to manage distinct types of housing, including limits on who is forced to live in Bio-Trophy preserves or who gets to live in Luxury Housing rather than the regular stuff, but that's a new UI and not the current one. It would have value beyond just accommodating the Mermoids, too -- you could have a prison-planet with a special slave type ("Prisoners With Jobs") who got over-crowded if you didn't build enough jail-type buildings, for example.
There are concepts from the current game which could be implemented to bring more value in a new UI -- as mentioned, Luxury Housing and Bio-Trophy preserves would be in there -- but again, that's a new UI.
Aquatic is just one more biome type in this game, and we know how biomes like Arctic / Alpine / Desert / Tropical / Temperate are treated in the game. They're not treated like places on a planet.
That could have been done in Tiles -- it would have been pretty easy to make maps wider in the middle, with different biomes represented as tiles, so you get terraforming to change your desert tiles into something more livable, or you get a desert species to live on those tiles -- and in that context, aquatic species would fit in nicely.
Ocean City Districts are a fine idea, but again how does that work in terms of the current UI? Even pops which are supposed to be housed specially are mechanically represented by having jobs which incidentally provide housing. Those pops can't be given normal jobs. This is okay for that one use-case, but it's not a viable system for housing in general.
The current mechanics and UI would need substantive changes, and there is no obvious place for those changes to be represented.