As long as the have a mouth, you can frag them
and if you don't want to, they will be fine as well.... the little ones will stretch into the light at least part of the day, I mean if they're growing, they will be fine.....
Just, after you frag the mushrooms, if you do, don't try to glue them to anything, cause the will not stay, believe me, I've tried it a million times
you gotta put them in a covered container with holes so that it still gets light and flow, in the tank, with lr rubble in there until they attach to a piece