katwright

I have two tetras in my tank after my fat goldie just passed away. A white skirt and a berry one. I didn't know you not suppose to buy them but they get along well. I have a 20 gallon. Should I get more tetras like them to school? If yes how many and should I get other fishes?
Also do I need a heater? The water keeps getting coldish.:-(

TFA101

yes, set it to about 70-74 degrees. These guys are best in slightly cooler water in my experience. Get about 3 or 4 more of them and they will develop a pecking order among themselves. They can be nippy sometimes, but when kept in groups of 5+ they will socialize with each other rather than other fish. You could begin a community. A trio of 3 Bronze cories and a small shoal (3 or 4) cherry barbs should work out nicely.

Devon

You should definitely get more of each kind. They like to school with their own kind, and in my experience won't be happy unless there are at least 5. 6-12 seems to be the ideal range for tetras.

Blub

They are tropical fish, so get them a heater, and a thermometer. They need 78F - 80F ideally. Get about 5 more of each!

Steen16

i find it best to have 10 it keeps them bizy swimming around each other and makes them feel safer