I currently have 4 black neon tetras which i understand should be in groups of 6+. Could i add 4 neon tetras to make up the numbers, or does it have to be the one spcific breed i.e add 4 more black neon tetras.
I've found that tetras of similar size will often school together... I've had black neons and regular neons school together... black skirts and columbian tetra.. I'm not saying this is always the case, I've just seen it in my tanks.