Pull a Lucky Fish Best Fish: Income, Rarity & Keep-or-Replace Guide
Choose the best fish for income or collection by comparing displayed earnings, mutation effects and upgrade costs, with clear examples.
Which is the best fish to keep?
For income, keep the fish with the higher current money-per-second value. For collection, keep a fish you still need in the Index. A species-only S/A/B list cannot account for an upgraded or mutated fish, so the table below ranks what to do with a catch instead of pretending every copy has the same value.
| Priority | Your catch | What to do |
|---|---|---|
| Keep for income | Higher displayed income than your weakest placed fish | Replace the weaker earner |
| Keep for collection | An Index entry you have not completed | Complete that entry before selling or sacrificing it |
| Keep for a mutation project | A spare fish carrying a wanted mutation | Compare the extraction method before disposing of it |
| Compare before investing | A rare fish with lower income than an upgraded common | Calculate upgrade cost and added income first |
| Replace last | Your strongest current earner | Do not sacrifice it merely to roll a random reward |
A mutated fish can beat a rarer unmodified one
Worked example only: fish A earns 100/s before a single 4× modifier, producing 400/s under that assumption. Fish B displays 350/s. A wins the income comparison by 50/s even if B is rarer. If A’s interface already shows 400/s, do not apply 4× again.
The mutation reference includes the July guides’ reported multipliers and later method changes. It does not provide a universal formula for multiple stacked mutations.
Named fish and rarity claims
The collected gameplay mentions Alien Fish, Prism Fish, Codfish, Sunfish, Dolphin and Voidfish. Voidfish appears in rare/secret-fish context. That supports a reference entry, but it does not establish that Voidfish always out-earns every other species at every level.
Use the fish list with video timestamps for those observations. The newer float guide also distinguishes Beast-related rolls from mutations; a Gold or Bloody prefix describes a mutation, not a standalone fish rarity.
How much is an upgrade worth?
Subtract the current rate from the upgraded rate. Divide the upgrade price by that increase. Example: a 30,000 upgrade that adds 100/s repays in 300 seconds, or five minutes, if income continues at the same rate.
If you will replace that fish sooner than the payback time, saving for a rod or using a free better catch can be the better option. This is a calculation from your inputs, not a prediction of which rare fish will drop next.
Beginner versus endgame priorities
Starting out: fill available island spaces and make the return reliable. Progressing: remove the rod or training limit preventing farther casts. Optimizing income: compare actual rates, paid upgrade returns and mutation options. Each step gives you a decision you can act on without a made-up maximum fish value.