Mutations and multipliers

Quick answer

Mutating fish multiplies their sell value; the game never prints the multipliers, so player-measured numbers are the only reference we have.

Mutations are how the same fish turns into real money in Deep Fishing. The problem: the game never shows you the multipliers. There is no table in-game — the numbers below exist because players sat down, mutated the same fish repeatedly and measured the difference.

Measured mutation multipliers

<div class="tbl-wrap"> <table> <thead><tr><th>Mutation</th><th>Multiplier (player-measured)</th><th>Notes</th></tr></thead> <tbody> <tr><td><strong>Diamond</strong></td><td class="num">8x</td><td>The biggest measured jump</td></tr> <tr><td><strong>Electro</strong></td><td class="num">5x</td><td>Second-highest recorded value</td></tr> <tr><td><strong>Toxic</strong></td><td class="num">4x</td><td>Reliable mid-tier multiplier</td></tr> <tr><td><strong>Gold</strong></td><td class="num">~2x</td><td>Reported as roughly double</td></tr> <tr><td><strong>Wet</strong></td><td class="num">~1.5x</td><td>The smallest of the measured set</td></tr> </tbody> </table> </div>

Treat these as a working reference, not as developer-confirmed values: they come from player tests on the current build, and mutations are exactly the kind of system that gets retuned in a patch.

Why mutating matters twice

Mutating a fish raises what it sells for, and it raises what a pond stocked with that fish pays out per minute. That second effect is the one people miss — a mutated fish in your pond is a passive multiplier that keeps working while you do something else entirely.

Official Deep Fishing screenshot: a haul of coloured, mutated fish on the line

The scroll rule everyone learns the hard way

There are two kinds of mutation scroll:

Normal scrolls — cheaper, and they carry a risk: they can reduce a fish's weight.
Ultra scrolls — they apply the mutation without the negative downside.

So the practical advice is simple. Roll normal scrolls on fish you do not care about. Save ultra scrolls for the fish that are already good — the physical weights you intend to keep or to stock your pond with.

A working mutation routine

Catch a big one first. A multiplier on a small fish is still a small fish. Weight first, mutation second.
Roll in batches. Apply scrolls to several fish at once; the point is to find the high multipliers, not to perfect one fish.
Keep the winners, sell the rest. Pond gets the heavy mutated ones; the bag gets sold.
Watch the label. A gold or wet fish is still a mutation, but at 2x and 1.5x it is not worth the same scroll you would spend chasing a diamond.

Then what?

Mutation value is the biggest single multiplier you control after your upgrades, which is why late-game players build their sessions around two things: making the cast reach deeper water, and making every fish in that water worth more before it hits the bag.