Fisch: How to Obtain the Secret Stellar Vengeance Skin

Stellar Vengeance is a hidden skin for the Stellarwave Melody, the Stage 8 keytar rod added to Fisch in the Astral Observatory update. It does not appear in any shop, it is not a quest reward, and nothing in the journal points you toward it. The unlock is a single hidden interaction tied to one very specific fish.

Quick answer: Equip the Stellarwave Melody, catch a Treble Bass with the Synth mutation at Roslit Hamlet, then warp to Boreal Hollow, hold that fish in the hidden piano room, and click the piano repeatedly until the skin unlocks.

What you need before the unlock will trigger

Every part of this depends on already owning the rod. The Synth mutation is rolled by the Stellarwave Melody itself, so there is no shortcut for players who have not finished Lyren’s questline yet.

Requirement	Details
Rod	Stellarwave Melody, a Stage 8 rod obtained from Lyren’s questline. Level 1000 required.
Fish	Treble Bass carrying the Synth mutation
Fishing spot	Roslit Hamlet
Unlock location	The hidden piano side room inside Boreal Hollow
Mutation odds	8.8% chance for Synth on every catch made with the Stellarwave Melody
Added in	Version 1.99.1

Lyren only appears in a side room at Boreal Hollow during a Celestial Congregation, the Astral Anomaly triggered by mounting the Stellar Lens in Astronomer Vega’s telescope. Boreal Hollow itself is a hidden cave on Boreal Pines, reached through a glowing portal near the lake in the island’s upper area.

Catch a Synth Treble Bass at Roslit Hamlet

Equip the Stellarwave Melody. The rod’s own mutation table is what produces the Synth roll, so nothing else in your inventory will get you there.

Travel to Roslit Hamlet and fish for Treble Bass. At an 8.8% Synth rate, expect to reel in a stack of plain and Aurora-mutated Treble Bass before the right one appears.

Fishing for Treble Bass at Roslit Hamlet with the Stellarwave Melody equipped — Fishing at Roslit Hamlet for the Treble Bass that needs to roll the Synth mutation. Image: Fisch

Check the catch name before you move on. The fish has to read as Synth Treble Bass. Melody, Aurora, and Sparkling versions of the same fish will not work, and neither will a Synth mutation on any other species.

Keep the fish. Do not sell it, store it in your aquarium, or hand it to a quest NPC. You need it in your hands for the final step.

Unlock Stellar Vengeance at the Boreal Hollow piano

Warp to Boreal Hollow. If you have already been there once, the warp point saves you the trip through the Boreal Pines portal.

The Warping screen as the player teleports into the icy Boreal Hollow cave — Warping into Boreal Hollow, the cave that houses the hidden piano room. Image: Fisch

Head into the hidden piano room off the main cavern. It is the same style of tucked-away side room the questline uses, so look along the cave walls rather than the open fishing area.

Equip the Synth Treble Bass so your character is physically holding the fish, not the rod, when you walk up to the piano.

Click the piano repeatedly. The interaction needs several rapid inputs rather than one press, and the skin unlocks once the sequence registers.

Note: the fish is consumed by the interaction in the sense that the unlock is one-time, so there is no reason to hoard extra Synth Treble Bass afterwards.

How to confirm the skin unlocked

Stellar Vengeance shows up as a selectable skin on the Stellarwave Melody. Equip it and the rod’s default cyan and white keytar swaps to a pink and purple version with glowing visual effects, which is the fastest visual confirmation you can get in-game.

The pink and purple Stellar Vengeance keytar skin equipped while casting — The Stellar Vengeance skin recolors the Stellarwave Melody keytar in pink and purple. Image: Fisch

If nothing happens at the piano, the cause is almost always one of three things. You are holding the wrong mutation, you are holding a different fish species, or you are holding the rod instead of the fish. Re-check the item name in your hand before farming another Treble Bass.

What the skin changes on the Stellarwave Melody

Stellar Vengeance is cosmetic. The rod’s stat line and abilities stay exactly the same underneath it.

Stat	Value
Lure Speed	88%
Luck	244%
Control	0.1
Resilience	30%
Max Kg	Infinite
Line Distance	188m
Progress Speed	+24%

The Zodiac Wheel minigame, the mutation rolls, and the Stellar status effect from hitting all twelve signs all behave identically with the skin equipped. Swapping to Stellar Vengeance is purely a look, which is worth keeping in mind if you were hoping the hidden unlock came with a hidden buff attached.