Confused Blue Acara ?

[zesty]

Hi, I added a Blue Acara to my tank the other day and I have noticed that he sometimes shoals with my Tiger Barbs. The Acara and Barbs are about the same size. I also got myself a Rotkeil Severum (again same size) and he has shoaled on the odd occasion.

Is this usual?

 

[Davo86]

fish shoal for security so it suggests that it isn't completely secure in its environment