The Cusk Purger is a craftable fishing rod added with The Deep expansion in Fisch. You earn the right to build it by finishing the main questline given by Chief Engineer Nereus, gathering seven deep-sea materials, and paying the crafting fee at the Ancient Archives altar.
Quick answer: Complete “The Deep” questline through Chief Engineer Nereus, upgrade your Deep Survey Device to MK II, survey the four collapsed pillars in the Gloomy Crevice, defeat the Monstrous Cusk for its tooth, then craft the Cusk Purger at the Ancient Archives altar for 750,000 C$ using the seven required materials (three of each).
What you need before crafting the Cusk Purger
The rod is locked behind progress in The Deep, not a straight purchase. Two things gate it. First, you must advance far enough in the Nereus questline to receive a Monstrous Cusk Tooth. Second, you need a MK II Deep Survey Device, because its Light Module is the only way to see and survey the collapsed pillars in the Gloomy Crevice.
The Deep Survey Device upgrade also carries several stat chips that support the Harpoon Guns you use to hunt the Monstrous Cusk. Those chips are what make the fight and material grind manageable.
| Survey Device MK II chip | Effect |
|---|---|
| Trench Running Enhancer MK I | +12 Movement Speed while underwater |
| Calibration Chip MK I | +10% Accuracy on all Harpoon Guns |
| Stabilizer Chip MK I | +15% Resilience on all Harpoon Guns |
| Power Chip MK I | +5% Power and +100,000 Max KG on all Harpoon Guns |
Finishing The Deep questline with Chief Engineer Nereus
Cusk Purger crafting materials and cost
The recipe calls for three of each of seven materials plus a flat currency cost. Abyssal Bio-Fluid and the Radiant Prism Scales tend to be the slowest to farm, so plan to spend time collecting drops before the altar unlocks the full recipe.
| Requirement | Amount |
|---|---|
| Monstrous Cusk Tooth | 3 |
| Line of the Deep | 3 |
| Refined Scrap | 3 |
| Hardened Chitin | 3 |
| Abyssal Bio-Fluid | 3 |
| Radiant Prism Scale | 3 |
| Ancient Bone | 3 |
| Crafting cost | 750,000 C$ |
Crafting the rod at the Ancient Archives
You know it worked when the Cusk Purger appears in your rod inventory and can be equipped. If the recipe will not complete, the usual reasons are a missing material count, not enough C$, or an unfinished Nereus quest that has not yet handed over a Monstrous Cusk Tooth.
Cusk Purger stats and passive ability
The Cusk Purger is built for high-value catches. Its passive creates a vacuum effect that pulls predatory deep-sea monsters straight to your line, and its base luck sits very high. Weight capacity is uncapped, shown in-game as infkg.
| Stat | Value |
|---|---|
| Lure Speed | 88% |
| Luck | 225% |
| Control | -0.05 |
| Resilience | 25% |
| Max KG | infkg |
| Progress Speed | +40% |
| Disturbance | +7 |
The reeling minigame uses slashing mechanics similar to the Titanium Rod, but the Cusk Purger has stronger stats and a better chance at mutated fish. One current limitation is cosmetic. The “Monstrous” mutation caught with this rod does not yet have its own visual effects.
With the questline cleared, the tooth in hand, and the seven materials stocked, the only step left is the altar. Bank the 750,000 C$ ahead of time so the craft goes through the moment you reach the Ancient Archives.
