The heaviest tuna I ever landed was a roughly 115-pound yellowfin. But the meanest one was a 90-pounder that almost killed me. I mean the danged thing just refused to give up, and I almost threw the rod, reel and stand-up belt overboard in capitulation.

So I can't imagine hooking into the monstrous tuna videoed by a remotely operated vehicle inspecting a deepwater Gulf of Mexico rig.

Watch the attached video to see this brutish fish, which has been estimated to be 18 feet long.

The Youtube video was shot a couple of years ago, and the size of the fish was estimated based on the known size of the rig's riser being inspected by the ROV operator.

The riser is 4 feet across, and the huge tuna swims right next to it to provide a telling measure.

What kind of tuna is it? That's up for debate.

The current IGFA record yellowfin tuna weighing 427 pounds was caught in 2013 off of Mexico. However, anyone who's ever been on a boat when a magnum yellowfin has been caught would expect to see sweeping sickle fins, which aren't present on the tuna in the vid.

A bigeye tuna, perhaps? This species certainly gets pretty daggone big. The current world-record Atlantic bigeye tuna went 392 pounds, 6 ounces. But the fish in the video simply has to weigh more than that, if it's anywhere close to 18 feet long.

The reigning world-record bluefin tipped the scales at a hefty 1,496 pounds — and according to Bob Shipp's Guide to the Fishes of the Gulf of Mexico they can be longer than 10 feet and weigh as much as 2,000 pounds.

But the coloration doesn't look right for a bluefin.

What do you think?