I would definitely contact the strata council - ask for a gallon amount because with something so vague as "a reasonable number of fish" they can decide What that number is After you've set up and they don't want it in the building! I mean, yeah, you could have just two fish (both sharks!) in a 400g system.... but I doubt they'd be cool with that
I was on my own strata council for years (SO glad to be done with it and be in a house now) and sadly that's the way it often works.