At this time I have 4 in my room. I am limited because:
1) I am out of electrical outlets.
2) I live at home with my grandparents while I attend grad school.. and they do not know about the fish (yes, I do not support sneaky behavior, but I'm 27 years old, work 3 jobs, care for their horses, care for their dogs ... by golly if I want a fish I'll have it).
3) Time. I teach 2 classes right now (one recently ended as a trimester course, I was teaching 3), I'm in 3 classes right now, I work at a pet store on the weekends, occasionally during the week I'm called into the family business to help with office work, I am very active in activities at school (not because I want to be, but because no one else will do it because they're "too busy"), I care for 40 horses and 8 dogs each day, and I'm trying to do my research so I can finally be done with grad school.