Farm Prism Scale and Radiant Prism Scale by going to the Outer Deep, finding the purple Formosa Seabass, and catching them with a harpoon gun until the scales drop.
Both scales arrived with The Deep, the game’s underwater expansion, and they come from the same place — one fish in one zone. Radiant Prism Scale is the one you’ll actually grind for, since it’s the rarer drop and it gates some of the update’s best rods.
Where to farm and what to target
| Item | How to get |
|---|---|
| Prism Scale | Catch Formosa Seabass in the Outer Deep — the common scale drop. |
| Radiant Prism Scale | Same Formosa Seabass in the Outer Deep — the rarer drop. |
Key Everything you need sits in the Outer Deep, the deepest area added by The Deep update. Your target is the Formosa Seabass, a purple fish that can drop both scales, and your tool is a harpoon gun — aim, fire, and reel it in. Prism Scale comes fairly often; Radiant Prism Scale is the rarer roll, which is why it decides how long you stay out there.
How to farm Prism Scale and Radiant Prism Scale from Formosa Seabass in Fisch
The whole loop is short — get into the Outer Deep, spot the purple fish, and harpoon it on repeat.
Travel to the Outer Deep
Head into The Deep, pass through Neriak, and keep going until you reach the Outer Deep — the farm zone, which opens up once you’ve unlocked The Deep.
Find the Formosa Seabass
Look for the purple-looking Formosa Seabass patrolling the Outer Deep waters.
Harpoon it for the scales
Aim your harpoon gun at the Formosa Seabass and reel it in; each catch can drop a Prism Scale and, less often, a Radiant Prism Scale.
Video help
Spotting the Formosa Seabass
The Formosa Seabass stands out because of its purple colouring, so once you know the shade you’re after it’s easy to pick out from everything else swimming past. In the bestiary it’s listed as an Unusual-rarity fish, and it’s the one species the whole farm is built around — both the regular and the Radiant scale come off the same fish, so there’s no second target to hunt down.
Speeding up the scale farm
Because both scales come from one fish, the fastest farm is just efficient repetition. Stay inside the Outer Deep and keep moving between Formosa Seabass spawns rather than parking on a single spot — every purple fish is a fresh roll at both scales. Radiant Prism Scale will always trail your Prism Scale count because it’s the rarer drop, so budget for a longer session when that’s specifically what you need. Drop rates here aren’t officially published, which makes catch volume your only real lever: the more Formosa Seabass you harpoon, the faster the Radiant scales stack up.
What Radiant Prism Scale crafts
| Use | Material needed |
|---|---|
| Cusk Purger Rod (Ancient Archives) | 2 Radiant Prism Scale |
| Luminous Rod quest (Dr. Vane) | 1 Radiant Prism Scale |
| Sightless Oracle Harpoon quest | 5 Radiant Prism Scale |
| High-tier Harpoon Gun recipes | 3 Radiant Prism Scale |
Radiant Prism Scale is an endgame material, and it’s tied to several of The Deep’s best rewards. The headline use is the Cusk Purger Rod, crafted at the Ancient Archives from Monstrous Cusk Teeth, Abyssal Biofluid, Ancient Bones, Hardened Chitin, the Line of the Deep and the Radiant scales themselves. It’s also a turn-in for Dr. Vane’s Luminous Rod quest and a step in the Sightless Oracle Harpoon line, and some high-tier harpoon recipes call for it too. The table shows how many each one wants — worth banking a buffer before you commit to a craft.
Farm a stockpile before you craft — the Cusk Purger Rod, Dr. Vane’s Luminous Rod quest and the Sightless Oracle Harpoon all draw from the same Radiant Prism Scale pool, so bank a few spares and one craft won’t wipe you out.
Farming mistakes to avoid
The biggest time-waster is fishing in the wrong place: these scales only come from the Outer Deep, not the overworld surface or the shallower Deep City pools, so if you’re not seeing purple Formosa Seabass you’re in the wrong zone. It’s also easy to trip over the name — Prism Scale has nothing to do with the Prismize or Prismatic mutations, which come from the Ethereal Prism Rod and are a completely separate system. And don’t expect Radiant Prism Scale to fall as often as the plain Prism Scale; it’s the rarer drop by design, so a slow Radiant streak is normal rather than bad luck.
Related Fisch guides
Frequently Asked Questions
Are Prism Scale and Radiant Prism Scale the same item?
No — they’re two separate drops that just happen to share a fish. When you land a Formosa Seabass, the game calls them out individually on screen, flagging the Radiant version as a Rare Find and the standard Prism Scale as an Extra Find. Radiant Prism Scale is the one endgame recipes actually demand, while the plain Prism Scale is the more common roll you’ll rack up along the way.
Can you get Radiant Prism Scale without a harpoon gun?
Yes. The harpoon gun is the quickest way to tag and reel in a Formosa Seabass, but the scale can also come from ordinary rod fishing in the Outer Deep — a high-luck Deep rod works fine if you’d rather not use the harpoon. The zone matters far more than the tool: as long as you’re pulling fish out of the Outer Deep, both scales are in play.
Is the 60.00% shown on the catch the real drop rate?
Treat it as the on-screen catch context, not a locked-in drop chance. The number that flashes up alongside a scale is tied to that specific catch’s notification, and the game doesn’t publish an official Radiant Prism Scale drop rate. What holds up in practice is the ordering — the Radiant scale drops noticeably less often than the regular Prism Scale — so plan around catch volume instead of a fixed percentage.
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