Slurpfloth

Slurpfloth is a Limited fish tied to the Octophant Hunt, and the wiki describes it as a lazy, sloth-like swimmer with drooping fins, nibbling slowly in dark water. It takes Fish Head bait, needs Rain and Winter, and has no time-of-day restriction. It is flagged as limited but is obtainable now.

Its average weight is 232.5 kg, from 95 kg to 777 kg, and the maximum ranks 178 of 663 fish. Value per kg is C$3.243, which gives an average sale of C$754.1, 353 of 742 documented fish by average value. Base XP is 1,700, a strong figure for something selling for that little.

Flamangler, Octophant, Orcanda, Royal Tigerfish and Shrimpanzee are the other Limited fish listed for the same hunt. That is a long list, so the hunt is the real event and Slurpfloth is one of several possible results.

Verdict: a decent XP source and an acceptable seller, not the main prize of the hunt. Go when the hunt is active, bring Fish Head, and wait for Rain in Winter. Keep the larger specimens for weight records and sell the lighter ones, since the payout depends heavily on how big the roll is.