My experience with these lil guys has been pretty good. I have 4, (one male , three females) and have successfully kept them for several months. Nearly a year. Theyve been thru many water changes and even recently a tank transfer. I have them in freshwater. Jus be sure to have them in a well planted tank with VERY good filtration and moderate circulation. Feeding them variety will help them live longer as well. Flakes, frozen bloodworms and brine shrimp. Very active fish to have and eyecatching color when they mature. I wouldnt recommend them for beginners. Very cool fish to have.
I've had these before and currently am starting a planted tank with them. They are really competitive between themselves but when a sufficient number of them is in the tank, 6-12 they don't nip at or bother other fish. I've no issue with them in tanks with inverts or dwarf frogs they leave shrimp and snails alone. Getting them to look their best is a chore its a combination of the right tank color pallet and backing with a good light but when they look good they are stunners. People say they are difficult to keep but I've only every noticed they don't like toxic water. In my early days I kept them for extended periods in less than ideal conditions and they flourished. They enjoy a current but don't need one if given an adequately sized tank. EDIT: Mine just spawned the second time that I've seen in as many weeks. The tank is barely cycled with still higher than ideal Ammonia and there they are spawning only seconds after I turned on the light this morning. They laid eggs in my java moss patch, sadly the black worms in there will eat the eggs soon as the light goes out. At any rate its a testament to how easy these little guys are.
My very reputable LFS keeps these in their slightly salted display tank... It's low-salt enough that there are plants, but there's salt in the water. Apparently these guys are really made for salted water, and in fact the store owner, who's great with rainbowfish in general, suggests keeping them in a tank that's set up to have just a bit of salt.
I have had for 1 1/2 years in soft water and no salt. The males are just beautiful. Water changes seem to motivate there breeding. Very peaceful the males don't bother the females as bad as others do. I have them in a community tank so getting a fry without them getting eaten is tough.