Let's say you're 68-year old Sue Elcock, all of 5'1" tall, on holiday from the UK. You go fishing on a boat near the town of Lancelin with your son Simon. Sue got a nibble and had to get some help to actually land the fish, for it took 40 minutes of reeling. Said Sue, when she first saw the head...it was the size of a sofa. Her previous largest catch was a snapper about a foot long. Her shock was a giant bass grouper two inches taller than her.
Tyrannosaurus Rex must have been larger. Nope, smaller, only up to 31,000 pounds. The largest dinosaur, the Titanosaur Argentinosaurus Huinculensis, was about 213,000 pounds, but that was a reptile, not a fish. The largest living creature ever on Planet Earth is probably still somewhere in the ocean. The Blue Whale weighs up to 400,000 pounds. But this is a whale, a mammal, not a fish.
Leedsichthys problematicus, probably bigger than a Whale Shark, but the 90-foot length seems like an exaggeration. There was the Megaladon, a shark, or fish, which only went extinct a couple of milion years ago, and was estimated to weigh 200,000 pounds, but this, too, is controversial. Anyway, did you know that the Blue Whale is the largest living creature ever on Planet Earth?