I have 13 in a 96X36 (LXW) tank. Size ranges from 3 in to 8 in. They're all active but I wouldn't say that the bottom of the tank is any where near "too active".
Don't sell any before you add your 15 to the new tank. I'm going to bet that with a 42 inch wide tank that you're going to want to add more.
Don't sell any before you add your 15 to the new tank. I'm going to bet that with a 42 inch wide tank that you're going to want to add more.