Prism Scale and Radiant Prism Scale both come from one fish in one place. The Formosa Seabass, a purple fish that swims through the Outer Deep, drops the regular Prism Scale often and the Radiant version far less. Radiant Prism Scale is the one you will grind for, since it gates several of The Deep update’s best rods.
Quick answer: Travel from The Deep through Nereus to the Outer Deep, find the purple Formosa Seabass, and catch it with a harpoon gun on repeat. Each catch can drop a Prism Scale and, less often, a Radiant Prism Scale.
Where both scales drop
Everything you need sits in the Outer Deep, the deepest zone added by The Deep update. There is no second fish to hunt. Both scales roll off the same Formosa Seabass, so the only variable is how many you catch.
| Item | Source | Drop frequency |
|---|---|---|
| Prism Scale | Formosa Seabass in the Outer Deep | Common (“Extra Find”) |
| Radiant Prism Scale | Same Formosa Seabass in the Outer Deep | Rare (“Rare Find”) |
The Formosa Seabass is listed as an Unusual-rarity fish in the bestiary. The drop rates are not officially published, so catch volume is your only real lever. The more fish you reel in, the faster the Radiant scales stack up.
Reach the Outer Deep and farm the scales
Confirm the drop worked
When a Formosa Seabass gives up a scale, the game flags each drop on screen individually. A standard Prism Scale shows as an Extra Find, while the Radiant version shows as a Rare Find. You will see messages like Extra Find! You just caught a Prism Scale! (1/2) and Rare Find! You just caught a radiant Prism Scale! (1/10).
Note: The percentage that flashes up with a catch is the on-screen notification for that specific catch, not a locked-in drop chance. The game does not publish an official Radiant Prism Scale drop rate, so plan around how many fish you catch rather than a fixed number.
Farm the scales faster
Because both scales come from one fish, the fastest farm is efficient repetition. Stay inside the Outer Deep and keep moving between Formosa Seabass spawns instead of parking on a single spot. Every purple fish is a fresh roll at both scales.
The harpoon gun is the quickest way to tag and reel in the fish, but it is not the only option. The scale can also come from ordinary rod fishing in the Outer Deep, and a high-luck Deep rod works fine if you would rather not use the harpoon. The zone matters far more than the tool.
Radiant Prism Scale will always trail your Prism Scale count because it is the rarer drop, so budget for a longer session when that is specifically what you need. A slow Radiant streak is normal rather than bad luck.
What Radiant Prism Scale crafts
Radiant Prism Scale is an endgame material tied to several of The Deep’s best rewards. The headline use is the Cusk Purger rod, crafted at the Ancient Archives alongside Monstrous Cusk Teeth, Abyssal Biofluid, Ancient Bones, Hardened Chitin, the Line of the Deep, and the Radiant scales themselves.
| Use | Radiant Prism Scale needed |
|---|---|
| Cusk Purger Rod (Ancient Archives) | 2 |
| Luminous Rod quest (Dr. Vane) | 1 |
| Sightless Oracle Harpoon quest | 5 |
| High-tier Harpoon Gun recipes | 3 |
Tip: These recipes all draw from the same Radiant Prism Scale pool, so bank a buffer before you commit to any single craft. A few spare scales mean one project won’t wipe out your stock.
Common farming mistakes
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. If you are not seeing purple Formosa Seabass, you are in the wrong zone.
The name also trips people up. 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 do not expect the Radiant version to fall as often as the plain Prism Scale, since it is the rarer drop by design.
