Two to five bristlenose plecos should be kept together. Bristlenose plecos are generally solitary fish. However, they can tolerate several other plecos, given that the tank is large enough.
A bristlenose pleco can grow to be five inches long, and it requires plenty of space to live comfortably. You’ll need a 25-gallon tank for a single bristlenose pleco without accounting for any other fish you might want to keep. Add at least ten gallons of water for each additional bristlenose pleco. In order to keep five bristlenose plecos, you’ll need a large 55-gallon tank.
Male bristlenose plecos are very territorial and won’t hesitate to fight other males. You should try to keep only one male bristlenose pleco in the tank. Alternatively, you can consider keeping only female bristlenose plecos.