Flying Gurnard

Flying Gurnard is a Legendary fish from Sunken Reliquary, and its conditions are tidy: Shrimp bait, daytime, Clear weather and Summer. The wiki describes a bizarre fish that uses wing-like pectoral fins to walk on the seafloor.

It is a small fish with a big rate. A typical catch weighs 3 kg, between 2 kg and 8.4 kg, but it sells at C$675 per kg, for an average of C$2,035. That ranks 258 of the 742 documented fish, so it sits in the upper half, even though its maximum weight ranks 479 of 663, which is on the light side. Each catch grants 1,326 base XP.

This is the opposite of a bulk fish: you are paid for the rate, not for the kilograms. Since the bait is just Shrimp, the cost to try is low, and the main limit is waiting for a clear summer day. If you are building coins and XP at the same time, it is a solid choice, and since it is obtainable, there is no rush. Keep one only if you track Legendary fish; otherwise sell it and move on to the next cast.