Convicts in a 33 gallon should be fine but it would have to be a species only tank. You could also keep german or bolivian rams in a 33 gallon. They stay pretty small, about 2-4 inches.
Guppy's don't necessarily need hard water. I have guppy's that are doing great and I have very soft water. In a 30 gallon tank you could probably have 10-20 guppy's.
i want to start breeding bolivian rams. I have a 29 gallon that's completely cycled with 3 goldenwonder killifish in it. Can i leave the golden wonder killifish in the tank or should i move it to my 20 gallon? I've done a lot of reading and i've seem that you're supposed to buy 6-8 rams and let...