We face the problems that biotopes are lost but most species are present at
hatcheries (an information I found just recently when researching it) and
many are in ponds. Frankly I must say that I am bound to colors and
reproduction biology. I plan to put in some Rhodeus (from the wild - don4t
tell around!;-) into one of my ponds. Maybe some ninespine sticklebacks too,
less probably some threespine as well. They like flowing waters, little
creeks and are not that suitable for a pond. And they are very aggressive.
The other native fishes we have are of no interest for me despite their good
taste. Fishermen and administration care for them (not too much but they
do). I am aquarist down to the roots. Therefore I am not at all interested
in humpbacks or trouts even if they are spectacular fishes in one or the
other way.
I know from here I cannot do much to help you preserve your own species, but
I am fascinated by many species4 color and/or ethology. Thus I like to keep
them and make them accessable for aquarists over here. And of course, e.g.
welaka, hubbsi or cardinals, it4s a challenge to breed these species and by
this possibly help to take of a bit of the collection pressure. That4s all,
not much but more than nothing. We don4t have fishes like darters or madtoms
here, only some sunfish and catfish invaders - literally everywhere.