Crescent Madtom

Crescent Madtom is a Rare fish from Blue Moon Sea 2, part of the Second Sea. It bites on Lushrooms in Rainy weather during Winter, at any time of day. The in-game text calls it a small, feisty fish with glowing eyes.

For a Rare it gives a lot of XP. It weighs 3 to 18.9 kg and averages 6 kg, and at C$158.333 per kg an average catch brings about C$950 and 3,820 base XP. Its average value ranks 329 of 742 documented fish, which is in the upper half, while its max weight ranks 409 of 663, so it is on the lighter side.

Nothing in the listing mentions a rod sold in the zone or other fish at the same rarity, so the plan is simple: bring Lushrooms, wait for rain in winter, and cast at whatever hour suits you.

That Winter-and-Rain requirement is the real filter. If you happen to be fishing Blue Moon Sea 2 when the weather lines up, swapping in Lushrooms is a cheap way to pick up nearly 4,000 XP and a respectable sale. Outside those conditions, it is not worth the detour.