I've seen pictures of this monster gatf and it's victims before. The size difference between the victims is considerable. And yes, this is probably the same type of sp of gatf that I have as well.. they grow very fast and gets more aggressive as they get larger and more mature. Mine takes chunks out of my BD stingray... which I thought the gatf would leave the bottom dweller alone. But I caught him in the act once as we the stingray climbs the wall and cruises around, it seemed to annoy the gatf and would do a pass by at him.. obviously he's not trying to eat the BD but just to show who's boss...
Regardless though, this guys setup is super boss. Makes me feel like mine is just a jail cell for the gatf...