If there is I've never heard of it. As long as the tank is cycled and water tests are good There plenty of different fish you can get. Just don't get ones that need mature tanks.
i disagree whole hearttedly there is most certinally fish that must be kept in an aquarium!!! any fish that you like to look at and keep you in the hobby and interested enough to care for the tank on a DAILY basis, and that will fit in your tank
:thinking: i'll personally always have a blenny, i think. certainly not necessary, but seems to keep everything in check and moving along.
as far as definite, i'd go with cleanup crew rather than fish. tanks are way more interesting without fish anyways.
imo