When dealing with ATF failing when cohabbed, it's not a question of if, but when. Sometimes you'll get years, sometimes only weeks. Sooner or later, there's only one left.
And I'll wager that once that fatf gets comfy, he'll start harassing the goliath.
Well the picture is the greatest. So I can't give an exact ID but if it isn't one of the vatf type it can only be batf with the adipose being black. Unless it's blue in person then you may have a real tatf.
VATF can have a blue adipose as well, it's just a lot more common in TATF. The problem is that TATF is basically completely absent from the hobby.
That fish looks like a skinny, fresh import VATF to me.