Deep Fishing on Roblox is a fishing simulator where you cast your rod across different worlds and reel in aquatic creatures of varying sizes and rarities. Mutations are the fastest way to multiply your earnings, both from selling fish and from passive Pond income. As of the Halloween World Update, there are 11 mutations in the game, and knowing which ones to chase makes a real difference to your cash flow.
Mutation Dealer reroll odds
How do mutations work in Deep Fishing?
Every mutation boosts a fish's sale value and its earning rate when placed in the Pond by a fixed multiplier. A Cosmic mutation, for example, turns a fish into a 15x earner compared to its base value. Mutations also change a fish's appearance visually, so a Gold mutation gives it a shiny golden look, while Toxic shifts it to a radioactive green.
Only one mutation can be active on a fish at a time. If you land a fish with a weak mutation and want to upgrade it, the Mutation Dealer NPC on the starter island handles that. Equip the fish, talk to the Dealer, and spend Mutation Rerolls to spin for a new mutation. The Dealer's menu shows the odds of every mutation on the right side of the screen before you commit.
How do you get mutations on fish?
There are three distinct ways mutations appear on fish.
Natural mutations (no event required)
Gold and Diamond are the only mutations that can spawn on fish at any time, regardless of weather. They appear through random chance while fishing, so you can catch them during any session on any server.
Weather event mutations
Nine mutations are tied directly to weather events that cycle every few minutes on a server. When the matching event activates, fish in the sea have a chance to carry that mutation. The developers can also trigger these events manually during Admin Abuse events.
Here is every weather-dependent mutation and its trigger:
- Cosmic spawns during the Cosmic weather event
- Lava spawns during the Volcano weather event
- Bloodlit spawns during the Bloodmoon weather event
- Cursed spawns during the Cursed weather event
- Electro spawns during the Thunder weather event
- Toxic spawns during the Toxic weather event
- Frozen spawns during the Blizzard weather event
- Wet spawns during the Rain weather event
Pearl mutation (Captain Fathom)
Pearl is a special case. To apply it, you need to obtain Pearls from Captain Fathom and use a Pearl directly on a fish. This method bypasses the weather system entirely.
All Deep Fishing mutations ranked by multiplier
The table below lists all 11 mutations, their multipliers, and how to obtain each one.
| Mutation | Multiplier | How to Get |
|---|---|---|
| Cosmic | 15x | Cosmic weather event |
| Lava | 12x | Volcano weather event |
| Bloodlit | 12x | Bloodmoon weather event |
| Diamond | 8x | Random spawn (no event needed) |
| Cursed | 6.5x | Cursed weather event |
| Pearl | 6x | Use a Pearl from Captain Fathom |
| Electro | 5x | Thunder weather event |
| Toxic | 4x | Toxic weather event |
| Frozen | 3.5x | Blizzard weather event |
| Wet | 2.5x | Rain weather event |
| Gold | 2x | Random spawn (no event needed) |
What are the best mutations to keep?
Cosmic, Lava, and Bloodlit sit at the top. Cosmic's 15x multiplier is the highest in the game, and both Lava and Bloodlit share a 12x multiplier. If you catch fish during these events, those are the ones worth placing in your Pond for passive income. Sell everything else unless it carries Diamond (8x) or Cursed (6.5x), which are also strong enough to hold onto.
Diamond deserves a mention because it can appear at any time without a weather event. Catching a Diamond fish during a quiet server is genuinely useful since you are not waiting on event timing.
Gold and Wet are the weakest options at 2x and 2.5x respectively. Sell fish with these mutations and reinvest the cash into better rods or Mutation Rerolls.
Pond passive earnings per fish
Mutation tier list at a glance
S tier: keep in your Pond
- Cosmic (15x)
- Lava (12x)
- Bloodlit (12x)
A tier: worth holding
- Diamond (8x)
- Cursed (6.5x)
- Pearl (6x)
B tier: sell or reroll
- Electro (5x)
- Toxic (4x)
- Frozen (3.5x)
C tier: sell immediately
- Wet (2.5x)
- Gold (2x)
How to get Mutation Rerolls
Standard Mutation Rerolls drop from fishing. The longer you fish and the higher your Luck stat, the more rerolls you accumulate over time. Ultra Rerolls, which increase the odds of landing higher-tier mutations, are purchasable with Robux at 39 Robux each.
The Mutation Dealer is located next to the Group Chest on the starter island. You cannot miss it once you know to look there.
Making the most of your mutated fish
The core loop is straightforward: sell fish with C and B tier mutations to fund better gear, and stockpile S and A tier mutated fish in the Pond for passive income. Rods with high Luck stats make a noticeable difference when weather events are active, since you are casting more efficiently during the limited window.
For free resources to speed up this process, check the Deep Fishing codes for October 2026 for working codes that hand out free Cash, Baits, and Potions. If you play other Roblox fishing games, the Fishing Master codes for October 2026 and Fisch codes are worth bookmarking too.
For more Roblox fishing content and strategy breakdowns, the full Roblox guides collection covers everything from rod tier lists to event walkthroughs.
