If that Gar attacked my Armatus the same way it attacked my ATF, I'm sure it would NOT have recovered.
I would say my ATF is way more aggressive with the feeders as soon as I put them in, he chases them and eats one, the Armatus waits and eats when he feels like it and doesn't really chase them, but I would also say he eats 2 and 3, where the ATF only eats 1 per night.
That ATF healed faster than anything I've ever seen and you should have seen how bad it really was, I thought he was done. Yet he grows very slow.
The ATF is not skittish in any way, when I get close to the tank he gets very curious and swims right up in my face while the others hide in the corner together.