Yes, when you move them into the 55 gallon tank, they will shoal. Prior to my 125 gallon tank, most of my current fish (including harlequin rasboras) shoaled in the tank. I also used to have neon tetras that shoaled as well in the same tank. When I moved the harlequins in my 125 gallon (6' long), the shoaling looked allot nicer, compared to a 55 gallon (4' long) tank.