the BTA vs Powerhead pay-per-view event was likely my post
They will wander until they find a spot they like. Mine kept hanging out in dark crevaces away from the light and then would take a little midnight stroll. I thought the PHs were safe......nope.
If you are looking at clowns to host in a BTA then you should look at false percs (ocellaris). I have two true percs and they preferred the area by the overflow box and totally ignored the BTA in the tank even when it was right beside them.