would you mind listing those fish and the min size tanks they can be housed in? not for my current tank, but as research for a potential future tank (or tanks)
Some appropriate temperate North American species include:
Any species of darter in the genus
Etheostoma. These are all suitable for 10 gallon or larger tanks. These are beautiful small bottom-dwelling invertivores, somewhat comparable to gobies.
Any species of darter in the genus
Percina. Some of these are suitable for a 10 gallon, but larger species, such as the logperches, need at least a 29/30 gallon. Similar to
Etheostoma but more midwater-active.
Any madtom (
Noturus species). These are small, nocturnal catfish. Most common species can live in a 10 gallon, but some, such as
N. flavus, need at least a 29/30 gallon.
Any species of shiner (several genera, including
Cyprinella, Hybopsis, Luxilus, Lythrurus, Notemigonus, and
Notropis), dace (
Clinostomus, Phoxinus, Rhinichthys), and some other minnows (
Campostoma, Hybognathus, Phenacobius, Pimephales, etc.). Avoid large chubs such as
Nocomis and
Semotilus species, as they will eat smaller fish. These are all schooling fish and vary widely in size; a small school of some of the smaller dace and shiners may be kept in a 10 or 20 gallon, while a school of
Campostoma or
Notemigonus requires a four-foot tank at minimum.
Any temperate freshwater killifish in the genera
Fundulus or
Lucania would also work.
I am sure there are many small species from other temperate regions that would work, but I never see them here in the states; the only temperate Old World species other than white clouds that I see are big bruisers like goldfish, carp, other big cyprinids, wimples, and dojo loaches.