My favorite fish is the Chocolate Gourami. It's not as rare as many of the others mentioned here, but keeping one alive and healthy is. Mine is nearly 3 years old and reaching the end of it's natural life. I had wanted one for over 45 years and finally got this one. Others I've had died rather quickly. I will mourn when it dies.
After 50 years I do a lot of things right, but still get things wrong
Its getting hard to find Zebra Plecos. If I understand, they are banned from being exported and also considered endangered. I long for the days when I saw them regularly at my LFS at affordable prices. Now it's hard to find them under $200 for an L46 Zebra Pleco. Very uncommon to see them in the "average" fish tank.
here in america it seems to be our own native fish...
i can just about count the number of people keeping warpaint shiners, or tangerine darters.
as for myself, i keep florida natives. i have encountered the Pteronotropis welaka, but its illegal to collect them in florida. im still looking for a source to buy them from. i want to breed them and spread them around. from what i understand of them, they really shouldnt be too hard to breed.
anyway, here is a short video of my bluefin killifish: