No problem! I currently have 3 cardinal tetras in mine. I hear the Edge can be a bit small for them as they can grow up to 2 inches in length. I'll most likely end up moving them over to my 46 gallon when it's complete. IMO, neons would be the more appropriate option as they are smaller and grow up to only 1.5 inches in length. Green neons look fantastic! However, at the moment the cardinals are doing just fine. I've had the tank set up for about seven months now. Hmm, shrimp seem to be a wonderful option for an Edge too.