Holy Catfish!

[Akasha72]

he needs to either be alone or with a female I think 

 

[TwoTankAmin]

Its usually about pecking order. Males do it and females do it as well. The males fight until an alpha male emerges. The alpha gets the best cave and he is the one all the girls want.
 
The females also fight to develop a pecking order. The top female is the one who gets to spawn with the alpha male.
 
When the space provided for multiple plecos of both sexes is not adequate or, when it is but the cover included is not, the fish will pretty much fight a lot of the time.
 
But the above is true for many species not just plecos.
 
Also, bn are pretty rough in terms of spawning behavior- males and females will tussle.
 
Zebra pleco males are known to trap lesser males in a cave and kill them to eliminate competition. And even when this is not the end result, they will still fight.

 

[Akasha72]

thanks TTA ... that's good to know but I won't be getting any more of them. It's good for others to know though so they can be aware of what can go wrong