How to Get Mutations in Deep Fishing

§Before you reroll a caught fish#

• Keep the caught fish you intend to change. Record its name, current mutation, size and displayed value so you can compare the result.
• The official announcement says Mutation Scrolls may be fished when lucky. It does not give a current drop rate, fishing zone or required rod.
• Inspect the live reroll control for eligible fish, required resources and any confirmation. Stop if the target or cost is unclear; no menu location or fixed price is verified here.
• Treat the action as a chance to change the fish. Preserve a mutation you already value unless you are willing to lose that result.
• After confirming a reroll, compare mutation and size separately before selling. The official notes mention both size increases and decreases.

§Which result are you trying to change?#

§How to interpret the published Rekin Shark chance#

The September announcement places a 0.1% Rekin Shark chance under Mutation Reroll. It does not explain the denominator, eligibility, separate controls or whether later updates changed it. Keep that figure attached to the historical announcement; it is not a verified current per-cast or per-scroll probability.

§First Mutation badge and the live result#

The official badge list includes First Mutation. A badge name establishes a milestone, while the live fish label establishes what your current catch carries. Record the mutation label and badge outcome separately when checking a new result.

For a collection goal, protect the catch before batch selling. For an income goal, compare the displayed value against the cost you actually paid. No universal mutation multiplier or most-profitable reroll is verified here.