How Many Pitbull Pleco's In A Pair?

[shadowhywind]

I recently gotten rid of my foot long common pleco and managed to find a lfs that had pitbull pleco's. I read that pitbull pleco's like being in pairs (2+), so when i picked mine up, they had a deal if I picked up 3. After about a week, one of the pleco's died on me. I didn't put much thought into it, and just thought that maybe it wasn't hardy enough for the tank swap. However after my brother saw mine, he decided to pick up some as well, and did the same deal of 3 pitbull pleco's. Well within 48 hours, one of his died. I am wondering do they "pair" up to only two. (aka, only get 2 or 4, etc)?? Or is this a random occurrence?

Btw, anyone who says pitbull's are not good algae eaters have never had pitbulls before! I never released what my common pleco did till i got rid of him. Within 2-4 weeks the glass was dirty and lots of algae. But within 1 week these 2 pitbull's had the tank sparkling! And they go crazy at feeding time, trying to keep my plants clean.