The best mutation in Deep Fishing is Cosmic, which multiplies a fish’s sell value and Pond earning rate by 15x. Lava (12x) and Diamond (8x) round out the top three, while Gold (2x) sits at the bottom. There are nine mutations in the game right now, and every one multiplies your income — you just need to know which ones to chase and which to sell instantly.
I’ve been grinding the seas since the Halloween World Update dropped, and this November 2026 tier list ranks all nine mutations by real money impact. Here’s the full ranking at a glance:
| Tier | Mutation | Multiplier | How to Get |
|---|---|---|---|
| S | Cosmic | 15x | Cosmic weather event |
| S | Lava | 12x | Volcano weather event |
| A | Diamond | 8x | Random catch, anytime |
| A | Cursed | 6.5x | Cursed weather event |
| A | Electro | 5x | Thunder weather event |
| A | Toxic | 4x | Toxic weather event |
| A | Frozen | 3.5x | Blizzard weather event |
| B | Wet | 2.5x | Rain weather event |
| B | Gold | 2x | Random catch, anytime |
How I Ranked Every Mutation?
Three factors decided each tier. First, the multiplier — a Cosmic fish sells for 7.5 times more than a Gold one, so raw value separates the pack quickly. Second, availability: weather-bound mutations only appear during their events, which rotate every few minutes per server, while Gold and Diamond can show up on any cast. Third, Pond value — mutations boost the earning rate of fish parked in your Fish Pond, so big multipliers keep paying long after the catch. I always value a mutation I can actually farm over a slightly better one I’ll rarely see.
S-Tier Mutations: Cosmic and Lava
Cosmic (15x) is the jackpot. While the Cosmic weather event runs, random fish spawn with galaxy skins that sell for fifteen times their base price. One Cosmic catch on a rare fish can fund a rod upgrade on its own, and in the Pond it outearns everything else you own.
Lava (12x) is nearly as profitable, and its Volcano event fires more often, which makes it the best realistic target for most players. My advice: idle at your best fishing spot and cast hard once Cosmic or Volcano weather goes live. My endgame setup is one Cosmic and one Lava fish of my best species parked permanently in the Pond for passive income, while every duplicate gets sold for instant cash. Hunting during the Halloween season? Our all 10 Ship Piece locations in Deep Fishing guide covers the rest of what Haunted Hollow is worth.
A-Tier Mutations: Strong Money Makers
Diamond (8x) is the star of this tier because it ignores weather completely — it can appear on any fish at any moment, making it the best passive earner in the game. Cursed (6.5x) has a spooky purple aura and spiked in availability during recent Admin Abuse events, when the developers trigger mutation weather manually. Electro (5x) is my favorite of the tier: Thunder events pop up frequently, and a 5x stack on a rare fish is serious cash. Toxic (4x) and Frozen (3.5x) are the entry gates — their events feel rarer, but the fish still sell well while you wait for something better.
None of these are keepers, though — sell A-Tier fish right away, or reroll them into something better if you’re attached to that particular catch.
B-Tier Mutations: Sell on Sight
Wet (2.5x) and Gold (2x) are early-game pocket money. They spawn often enough to pile up fast, but their multipliers are the weakest in the game. My rule is simple: sell every Wet and Gold fish immediately unless it’s your priciest rare, and never waste a Pond slot on them. Gold’s one redeeming quality is that it spawns naturally with zero event timing — perfectly fine while you’re still learning the ropes in World 1.
How to Get Mutations in Deep Fishing
There are three ways to get mutations, and I rotate through all of them:
- Weather events — Cosmic, Cursed, Electro, Frozen, Lava, Toxic, and Wet mutate random fish while their event is live. Events rotate every few minutes on each server, so hop servers if yours is quiet.
- Natural spawns — Gold and Diamond can appear on any fish, anytime, with Diamond being the 8x prize worth watching for.
- Mutation Dealer rerolls — the Mutation Dealer NPC, next to the Group Chest on the starter island (you’ll also spot him by the Fernshore leaderboards), adds or changes a mutation on any equipped fish. Each spin costs a Mutation Reroll earned from fishing, and every mutation’s odds are displayed in the top-right of the reroll menu.
Two pro tips before you spin: equip a rod with high Luck, because Luck improves your odds of hooking mutated fish in the first place, and save your rerolls for expensive rare fish — rerolling a common sardine is burning currency. If you go the premium route, Ultra Rerolls cost 39 Robux and roll noticeably better odds. Mutation hunting is the meta everywhere on Roblox right now: Steal An Egg players run the same grind (see our Steal An Egg mutations tier list), and Fisch anglers can chase that same spooky-season energy in our FischFright 3 trick or treat houses guide.
Common Mutation Mistakes to Avoid
I watch players burn coins on the same four errors, so dodge them from day one. First, rerolling low-value fish: a spin on a common catch usually returns another B-Tier result, so save Mutation Rerolls for fish worth ten times the roll. Second, selling S-Tier catches — that 15x Cosmic looks tempting at the shop, but a stretch of Pond income beats one sale almost every time.
Third, grinding through dead windows: weather events rotate every few minutes per server, so if a dozen casts produce zero mutations, hop servers instead of fishing an empty sea. Fourth, ignoring Luck upgrades — a higher-Luck rod pays for itself in mutated catches faster than any other purchase I’ve tested. Fix these habits and your coins per hour climb without changing how you play.
FAQs
What is the best mutation in Deep Fishing?
Cosmic, at 15x. It only spawns during the Cosmic weather event, so camp your best spot and cast hard while it’s live. Lava (12x) is the best farmable alternative.
How many mutations are in Deep Fishing?
Nine as of the Halloween World Update: Gold, Wet, Frozen, Toxic, Electro, Cursed, Diamond, Lava, and Cosmic. Updates tend to add more, so expect the list to grow.
How do you get mutations in Deep Fishing?
Three ways: random natural spawns (Gold and Diamond), weather events that mutate fish caught while they’re active, and Mutation Dealer rerolls using Mutation Rerolls or Ultra Rerolls.
Are Ultra Rerolls worth it?
Only for expensive rare fish. At 39 Robux each, they roll better mutation odds than the free Mutation Rerolls you earn from fishing — burn the free ones first.
Should I put mutated fish in the Fish Pond?
Yes. Mutations multiply a fish’s Pond earning rate exactly like its sale price. Keep 15x Cosmic and 12x Lava fish in the Pond and sell everything B-Tier.
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