Rainbowfish are beautiful fish; I had 5 praecox (dwarf neon) rainbowfish.
Unfortunately, they lasted 3 weeks. :sad
The problem with rainbowfish is that if they are stressed (whether through bad water, overcrowding, etc.), they are extremely susceptible to columnaris (gram-negative bacterial infection), especially in the form of mouth lesions. In this form it is called "cotton mouth" or "mouth fungus," because it involves white, cottony growth around the mouth area, and is often mistaken for a fungal infection. And while it sometimes can be treated successfully with rather strong antibiotics, often you can do everything perfect and the infection simply won't go away...once it gets a foothold, it can be impossible to successfully treat sometimes.
I know several experienced aquarists who basically have told me to never buy rainbowfish from a store...the odds are just too high they are already infected. Mine, which I bought from a rather reputable mom & pop fish store in town, developed columnaris within 10 days of me getting them home. Next time I was at that store, just on a lark, I took a good look at their rainbowfish tank. I would say a full 1/3 of the fishes in there had the beginning symptoms of cotton mouth.
The point of all this: rainbowfish are stunningly beautiful, great fun to have in a tank, peaceful towards everyone else, interesting, incredible "hunters" (put some live brine shrimp or live bloodworms in a tank with them and watch them go!), easy to sex (males have red fins, females have yellow), and in every other respect perfect fishes for your tank.
Just don't buy them from a store. Find a breeder in your area and buy directly from him or her. If you can do that, I guarantee you that you will be so thankful you put them in your tank. (P.S. -- They do great in schools, if possible best ratio is 2-3 females per male. Males will chase each other at times--nothing truly aggressive, just establishing a pecking order--and will also "flare" their fins at each other. Males will also flare at females in order to attract their attention. And I hear that if you have something soft like java moss in your tank, getting them to breed is not terribly difficult.)
Unfortunately, they lasted 3 weeks. :sad
The problem with rainbowfish is that if they are stressed (whether through bad water, overcrowding, etc.), they are extremely susceptible to columnaris (gram-negative bacterial infection), especially in the form of mouth lesions. In this form it is called "cotton mouth" or "mouth fungus," because it involves white, cottony growth around the mouth area, and is often mistaken for a fungal infection. And while it sometimes can be treated successfully with rather strong antibiotics, often you can do everything perfect and the infection simply won't go away...once it gets a foothold, it can be impossible to successfully treat sometimes.
I know several experienced aquarists who basically have told me to never buy rainbowfish from a store...the odds are just too high they are already infected. Mine, which I bought from a rather reputable mom & pop fish store in town, developed columnaris within 10 days of me getting them home. Next time I was at that store, just on a lark, I took a good look at their rainbowfish tank. I would say a full 1/3 of the fishes in there had the beginning symptoms of cotton mouth.
The point of all this: rainbowfish are stunningly beautiful, great fun to have in a tank, peaceful towards everyone else, interesting, incredible "hunters" (put some live brine shrimp or live bloodworms in a tank with them and watch them go!), easy to sex (males have red fins, females have yellow), and in every other respect perfect fishes for your tank.
Just don't buy them from a store. Find a breeder in your area and buy directly from him or her. If you can do that, I guarantee you that you will be so thankful you put them in your tank. (P.S. -- They do great in schools, if possible best ratio is 2-3 females per male. Males will chase each other at times--nothing truly aggressive, just establishing a pecking order--and will also "flare" their fins at each other. Males will also flare at females in order to attract their attention. And I hear that if you have something soft like java moss in your tank, getting them to breed is not terribly difficult.)
I have 2 in my cichlid tank. They're in there with kenyis, auratus, albino cichlids and they have no trouble holding their own. They can even stand up to 8.2ph, and these particular 2 withstood an ich attack the affected all the others.