DREDGE Aberrant Chance & Other Stats List

Aberrant chance is calculated as the sum of these values:

1. Time of day: Chance at daytime is 1%, chance at night is 3%.
2. Uncaught bonus: Each non-aberrant fish caught increases the chance. I can’t find the exact value though.
3. Spot chance: The glowing spots have a 35% chance, and guarantee at least 1 aberrant. These spots have a 2.5% chance to appear during the day, or 1% at night.
4. Gear chance: Set by certain rods, see stats here: https://dredge.fandom.com/wiki/Rod#Aberrant_Bonuses

Additionally:

• Aberrant fish only start spawning on day 5.
• The max aberrant spawn chance is 35%.

The exact stats are:

• aberrationStartDay: 5
• baseAberrationSpawnChance: 0.01
• nightAberrationSpawnChance: 0.03
• specialSpotAberrationSpawnBonus: 0.35
• maxAberrationSpawnChance: 0.35
• specialSpotChanceDay: 0.025
• specialSpotChanceNight: 0.1

Certain rods (or rod slot items) give a bonus chance to finding fish with aberrations.

The bonus listed here is a +% chance increase.

Note: I’ve also added this info to the wiki, which has images and shows slots, see here:
https://dredge.fandom.com/wiki/Rod#Aberrant_Bonuses

For Bait, I haven’t found an indication that it increases aberrant chance, but I can share the stats I did find:

• numCellsPerFishBait: 4
• numFishInBaitBallMin: 2
• numFishInBaitBallMax: 4
• numFishSpeciesInBaitBall: 4
• baitedTrophyNotchSpawnChance: 0.4

For Atrophy, it guarantees at least 1 aberrant fish, but they’re always rotting or infected. Here’s the stats I found:

• atrophyStockPenalty: -10
• atrophyGuaranteedAberrationCount: 1
• atrophyTotalParasiteChance: 0.5
• atrophyConditionMin: 0.75
• atrophyConditionMax: 1.5

I would guess the `condition` values there set the freshness. Max freshness (“fresh”) is 3 (see `maxFreshness` in Misc below), so stale must be 2, and rotting would be 1. So Atrophy fish are always rotting (1.5), and I’d guess that the atrophyConditionMin value of 0.75 would mean that it’s very close to become mush.

Research Parts have a small chance to appear when you dredge (7%). Apparently they also have a chance to appear in crab pots (2%), but I’ve never seen one appear this way, please comment below if you have.

• researchItemDredgeSpotSpawnChance: 0.07
• researchItemCrabPotSpawnChance: 0.02

Other interesting stats:

• Special spots have a 2.5% chance to appear during the day, or 1% at night.
• Fish lose their freshness by 1 rank every 12hrs, or 2 ranks every 24hrs. The max is 3 (Fresh), 2 is Stale, 1 is Rotting.
• Trophy fish have a 7.5% chance to appear, but you need to catch 5 fish before another trophy fish appears.
• The banish machine lasts for half a day, ie. 12hrs.
• Infection spreads at a rate of 0.2 days (4.8hrs), with a 15% chance for the infection to spread.
• There’s a stat related to infection/aberration called “swapChance”, which is 15%. It looks like this means that an infected fish has a 15% chance to become an aberration.

The exact data:

• specialSpotChanceDay: 0.025
• specialSpotChanceNight: 0.1
• freshnessLossPerDay: 2
• maxFreshness: 3
• trophyNotchSpawnChance: 0.075
• baitedTrophyNotchSpawnChance: 0.4
• fishToCatchBetweenTrophyNotches: 5
• banishMachineDurationDays: 0.5
• itemInfectionSpreadIntervalDays: 0.2
• itemInfectionSpreadChance: 0.15
• infectionAberrationSwapChance: 0.15

A player has reported that the DLC engine, “Arterial Engine”, increases its speed at night (source). I could not confirm this myself though, either in-game or from looking at the code. If anyone else can confirm this, please let me know.

Notes for fellow data miners: I got these values from dumping the game with AssetRipper[github.com]. The stats listed are from GameConfigDataProd.asset (eg `aberrationStartDay`). The aberrant chance is in ItemManager.cs, in the function CreateFishItem (search for the debug note “[ItemManager] aberration spawn chance”).

Also note that while these values are correct at the time of writing, they might be balanced differently in patches.