(not from the net!)
Do not just stick to the red nose! I wonder why nobody mentions their beautiful black and white tail! It is impressive to watch them swim around moving this cute little tail. I keep 6 of them in the tank along with 16 Cardinals and 6 Cherry Barbs. Nice, peacful fish, they manage to eat only after the barbs have had their lunch.
I have not had so many problems with water quality. But I do not change my water very often. I think that they prefer a well-planted and established tank with a medium speed filter. Mine are extremely active and absolutely safe with small fish, shrimp and long-finned fish like Guppies.
I've had rummy noses for about a decade and they have been one of the hardier fish in the tank. It's a planted 115 L tank, and contrary to all the specs, the only thing I treat the water for is chlorine/chloramine and the pH hovers around 7.5+. The temp is about 27°C and it's overall hard water. This latest school is at least 2-3 years old with bright red noses, good energy/appetites and no diseases, so for me, I've found them pretty easy to keep and beautiful to watch.
I had six of these beautiful little fish when I first started up my aquarium. They are very peaceful and VERY active. They like to race around in a tight shoal in the bottom third of the tank. Their colours and behaviour are the best when they are healthy and happy, and their noses are like a radar for the health of your tank - any problems and their colours fade. I have found that they really do need their own company (at least 4); they can be quite nervous fish and I rarely saw one swimming alone. When they are in good condition they are an absolute delight! BEWARE these fish jump! Once I was feeding mine with the tank lid off and a Rummy jumped right out and hit me in the snoz! Luckily he lived to tell the tale!
At one time, I had a school of 4 rummy-noses in my 120 litre community tank, but now sadly, only 1 remains. They are a great addition to any community tank, providing colour, and entertainment. Be sure that the tank is fully cycled and that they are NOT the first fish in the tank. Like most tetras of their size, it is a good idea to add them to a matured tank. They fully-grown adult size is around 5-6cm. Try to keep the pH around 6.5-7.0 like any other amazon fish. I am gonna replace the little critters very soon! = )
I've kept a shoal of 16 Rummy nose tetras in a 180 litre planted tank for 4 years now. These tetras seem to keep in a nice tight shoal compared to other tetras I've kept, including cardinal, Colombian, pretty and black tetras. I've had no problems with diseases or anything else, and would recommend rummy noses to anyone looking for a nice shoaling tetra.