I had two goldfish in a 20g tank. The one died and i am now left with one about 3-4" without tail. Its seems like it has been lonely sometimes when i happen to look over. I was wondering if i should get another one for it? I was thinking if its ok to get just another fan-tailed goldfish, or get a black moor. I have an AC 150, and am hoping to upgrade it to an ac200 soon.