One day I bought three Glass Catfish, because I've read they like to be in threes. But some time later one of them died and for last few months there were only two of them, and I didn't have the room for a third one. But recently I've upgraded the tank size and so I think there's place for one more, but the question is-- do I really need to get one? After all those month just the two of them won't they just stick to themselves and the third one end-up as an outcast? What do you reckon?