Very interesting question. Depends a lot on the tolerance level of fish towards changing environmental conditions. This in itself is very subjective at the very least but it makes better sense that the absolute worst case scenario is badly maintained tank that makes the fish more susceptible to health issues. Of course, if you consider again the fact your tank is quite small despite well maintained, the fish would still not be very comfortable in it thus it only adds up to its stress. Depending on your maintenance, if you are quite capable of frequent water changes to lift off the growth hormones released in response to stress by the fish which then inhibits its growth, then technically, the situation itself is a lot better than a tank, regardless of size, badly maintained.
