I had 4 and after about 4 month's there was 1 left. The funny thing was that the one ate the other on christmas day!!. I fed them about 4 times a week. And they were in a 55 gallon.
If you want all of them to live have lot's of hiding places for them and always keep feeders in the tank. lot's of plants help out alot and should be ok until they reach 4" then you will be in trouble.