In some languages (including English), certain words (verbs in English, for example) conjugate based off whether they refer to jost one or to more than one. Which form do you use when referring to less than one (whether a fraction, zero, or a negative amount), or if the quantity isn't a real number?
In some languages (not including English), certain words conjugate based off gender. It is sommon for the rule to be to use the masculine form unless it's an all female group. If you are referring to an empty group, which form should you use? (There's also the question what form to use if you're talking about a mixed group of women and non-binary people, with no men in it.)
A quick google search reveals that fish can, indeed, drown if their water doesn't have enough oxygen.
(There's also the case of a fish out of the water, but that's another story.)
Edit: fix -> fish (Yes, only just now (nearly a month after posting) did I notice that mistake.)