Those Gars look like monsters but the ones I've been around, Alligator Gars in Aquariums were pretty intelligent as fish go. They were quick to recognize faces and would beg to people that fed them, but not others. It was scary putting my hand in the tank at first but that passed. I would NOT hand feed mine though like I did some fish. I learned even fish without huge teeth can slice me up when my female dempsy ( I had her 7 years) accidentally sliced my finger open taking an earthworm by hand. In the water was fine but I made the mistake of holding it an inch above the water one time and she ended up with one finger in her mouth which sliced my finger before she let go and dropped back in. She was just exuberant when it rained. She knew ( by the lower pressure I guess) when it rained that I'd scoop up worms for her.
I really doubt I'd want to swim with the 5-6 on up foot Gars though I've only read about one attack on a human which sounded like mistaken identity.
Getting ones like the above in a small boat with you isn't recommended. They move quicker than it would seem. Even the scales can remoce skin in the right situation.
