I have one male red sided garter housed in a 20 gallon. I'm planning on buying a second garter from Scott Felzer when he's in stock (he says early 2011). I live close buy so shipping won't be a problem. I want to be sure I know everything I need to know about buying one. It will be another male.
Anything I should know putting him in the same tank? Anything I should watch for? Anything I should look for when picking one? etc. etc. I do know alot of what to look for, but anything will help.

Also is there any species that I shouldn't keep with a red sided? I know the whole 'wanderings are cannibalistic' thing and I'm staying away from them.
If they originate from completly different states, like Illinois and Texas will that matter?
It will probally be a month or two, but whatever.