Probably Stolen Fish Guide: Aquafarming Upgrades, Breeding, and Profits

Master raising and selling Probably Stolen fish with our complete aquafarming guide covering RAS tanks, breeding cycles, water purity, and fish fillets.

Running an underground pawn shop and workshop is tough enough, but mastering Probably Stolen fish production turns your cramped backroom into a self-sustaining financial powerhouse. In Probably Stolen, paying the weekly rent requires juggling multiple production lines, and adding fish farming to your shop rotation supplies both steady meat fillets and rare luxury trade goods. If you want to maximize your tank space and stop suffocating your stock, understanding how Probably Stolen fish mechanics work is essential for long-term survival.

Below, we break down every step of the aquafarming trade, from unlocking equipment to breeding schedules, tank filtration, and slaughter values.

How to Unlock Aquafarming in Probably Stolen

Before filling tanks with water, you must formally unlock the Aquaculture trade line. Players can start immediately as the Aquafarmer when building a new profile, or unlock the discipline mid-run through Joe Wild's contact network once reaching day 7.

Wild's Network (Day 7) ➔ Water Trading (300 Credits) ➔ Aquaculture (400 Credits) ➔ Aquaculture II (1,200 Credits)

Unlocking the starter tier introduces the Retired Aquafarmer, a weekly visiting trader who sells tanks, specialized feed, filters, and fertilized roe. Investing in Aquaculture II introduces luxury stock like eels and sturgeon.

Trade Unlock Requirements and Starter Bundles

Unlock Name	Prerequisite	Credit Cost	Included Starter Gear
Aquaculture (Tier I)	Water Trading Unlocked	400	Recirculating Aquaculture System (RAS), 12L Tank, Fertilized Tilapia Roe, Energy Cell, Rustwater Jug, Fish Feed, Kitchen Knife, Marking Pen
Aquaculture II	Aquaculture (Tier I)	1,200	Access to advanced stock (Eels, Electric Eels, Sturgeon), 2 Juvenile Eels delivered immediately
Aquafarmer Background	New Game Selection	Free (Starting Role)	Full Tier I starter kit, base tank setup, immediate fish farming focus

Setting Up Your Recirculating Aquaculture System (RAS)

Raising healthy Probably Stolen fish requires careful power management and clean plumbing. The core machine is the Recirculating Aquaculture System (RAS), an electrically powered life-support rig attached to an open tank.

[Energy Cell / Grid (5 Power/Night)]
           │
           ▼
┌──────────────────────────────────────────────┐
│  Recirculating Aquaculture System (RAS)      │
│  ├── 4x Internal Filter Slots (Water Quality)│
│  ├── Automatic/Manual Feed Dispenser         │
│  └── Connected Tank (12L Base Capacity)      │
└──────────────────────────────────────────────┘

Essential Setup Steps

Supply Power: The base RAS requires 5 units of power each night from an Energy Cell or direct shop wiring. If power cuts out overnight, your livestock begin suffocating immediately.
Pour Water: Fill the 12-liter tank. While basic Tilapia tolerate moderate contamination, high-tier specimens require cleaner water grades to prevent illness.
Equip Filters: Slot physical and chemical water filters into the four designated slots. Filters degrade over time depending on tank waste and water source purity.
Install Feed Dispensers: Mount a feeder loaded with standard pellets or chopped rations so your livestock grow automatically between daily cycles.

Upgrading Tank Dimensions

According to community reports and gameplay testing, players can modify and expand tank volume by spending raw resources. Using Scrap Metal expands tank width horizontally, while Metal Ingots (produced via smelting) expand tank depth downward. Expanding your tank is vital because an adult Tilapia requires up to 1 full liter of water volume; overcrowding quickly fouls clean tanks and kills fragile breeds.

Fish Species, Traits, and Utility

Not all Probably Stolen fish serve the same purpose. Certain species generate cheap fillets for market stalls, others purify dirty plumbing, and advanced species provide functional utility like generating electrical charges or medical supplies.

Fish Species Overview

Species	Source / Unlock	Primary Purpose	Unique Biological Trait	Breeding Behavior
Common Tilapia	Starter Kit / Retired Aquafarmer	Meat production	Grows 25% faster when fed raw meat or scraps	Breeds naturally in captivity (15% nightly chance)
Gutter Tilapia	Retired Aquafarmer (Roe)	Bio-filtration & low-grade meat	Removes heavy metals and chemical contaminants from dirty water; tolerates Rustwater	Breeds easily without player intervention
Eel	Aquaculture II (Wild Unlock)	Mid-tier fillets & specialty orders	Carnivorous; cannibalizes smaller tank mates if left unfed	Does not breed in captivity
Electric Eel	Aquaculture II Trader	Power Generation	Naturally recharges connected Energy Cells and tank batteries overnight	Does not breed in captivity
Medicinal Eel	Aquaculture II Trader	Pharmaceutical crafting	Skin can be sterilely excised and processed into high-grade bandages	Does not breed in captivity
Sturgeon	Aquaculture II Trader	Luxury goods (Caviar)	High market value; yields expensive roe and premium meat	Does not breed in captivity

Using Fish as Bio-Filters

One of the most clever production loops involves using Gutter Tilapia alongside water purifying systems in Probably Stolen. Instead of burning expensive water purification tablets or clogging pristine micro-filters on filthy Rustwater, player experience shows you can dump contaminated water directly into a tank housing Gutter Tilapia. These hardy creatures absorb chemical waste and heavy metals naturally over several days, leaving behind clearer water while slowly generating biomass.

The Breeding and Growth Cycle

To keep your supply chain moving without buying roe every week, you must establish an active breeding tank.

[Fertilized Roe] ──(1 Day)──> [Hatchling / Fry] ──(2 Days)──> [Juvenile] ──(5 Days)──> [Full Adult]
                                                                                             │
                                                                 ┌───────────────────────────┴───────────────────────────┐
                                                                 ▼                                                       ▼
                                                       [15% Nightly Breeding Chance]                               [Slaughter for Fillets]

Growth Milestones for Common Tilapia

Hatching (Day 1): Fertilized roe transforms into fry overnight inside powered, filtered water.
Juvenile Stage (Day 3): Fish become visibly larger. They consume more feed and can be butchered in emergencies, though juvenile meat yield is minimal.
Adult Stage (Day 8): Fish reach full biological maturity. Adults yield maximum fillets when butchered. Well-fed adult pairs share a 15% chance to produce fertilized roe each night.

Feeding Strategies and Cannibalism Warnings

Keep your livestock well-fed to prevent growth pauses. While Tilapia eat virtually anything—including cheap Gutterflow pellets and scrap vegetables—predatory species require protein:

Carnivore Diets: Eels refuse vegetable feed. They must be fed standard commercial fish feed, meat scraps, or rat pieces from your rat-ranching cages.
Predation in Mixed Tanks: Community reports frequently highlight an easy beginner mistake: putting juvenile Tilapia into the same tank as predatory eels. Carnivores will eat smaller fish swimming in their tank if food dispensers run empty, wiping out entire breeding populations overnight. Always separate aggressive species into dedicated tanks.

Harvesting and Fillet Price Values

Once your tank reaches carrying capacity, use a Kitchen Knife or slaughter station to process surplus Probably Stolen fish. Fish fillet size scales directly with the animal's life stage and overall mass at the moment of slaughter.

Fillet Sizes and Retail Values

Yield Item	Source Life Stage	Base Credit Value	Retail Markup Potential
Tiny Fish Fillet	Underdeveloped Fry / Small Scraps	13 Credits	Low; best used as carnivore feed
Small Fish Fillet	Early Juvenile	26 Credits	Moderate
Fish Fillet	Late Juvenile / Young Adult	57 Credits	Solid daily shelf seller
Large Fish Fillet	Fully Mature Adult (Max Size)	143 Credits	High; great for specialty food buyers
Luxury Caviar	Mature Sturgeon (Harvested)	High Premium	Sells exceptionally well during food crises

To maximize daily shop income, watch for community events like "Water Shortage" or "Food Supply Crisis" on your storefront calendar. Saving vacuum-packed large fillets and clean purified water for these crisis days yields substantially higher profit margins than selling raw catches immediately.

Best Practices and Pro Tips for Fish Farming

Maintaining consistent Probably Stolen fish margins requires staying ahead of equipment decay and tank accidents. Use these essential operational tips:

Label Breeding Pairs: Always use your Marking Pen on healthy adult breeders. If you automate your slaughter process or clear tanks quickly with a knife, marked breeders will remain protected.
Watch Water Saturation: Overcrowding a tank accelerates filter decay. If water quality drops from Basewater into Gutterflow levels, non-Gutter species will stop breeding, catch sickness, and eventually die.
Synergize with Rat Ranching: If you operate a rat breeding line, run raw meat trimmings and morsels into your fish feeders. Tilapia gain a 25% growth acceleration bonus when fed meat, speeding up maturity cycles significantly.
Charge Batteries for Free: Housing an Electric Eel in a secondary tank lets you trickle-charge spent Energy Cells every night. This substantially cuts down electrical expenses for running 3D gun printers, hydroponics, or metal smelters.

Frequently Asked Questions About Probably Stolen Fish

Can all fish species breed in Probably Stolen?

No. Only basic species like Common Tilapia and Gutter Tilapia breed naturally in your shop tanks. Advanced species unlocked through Aquaculture II—such as Eels, Electric Eels, and Sturgeon—do not breed in captivity. You must purchase replacement juveniles or fertilized stock weekly from the Retired Aquafarmer.

Why are my fish suffocating even though the tank has water?

Suffocation occurs when the tank lacks electrical power, when the water filter slots are empty, or when overcrowding exceeds tank capacity. Ensure your RAS unit receives at least 5 power per night, that internal filters are not broken, and that your tank provides at least 1 liter of water volume per adult fish.

How do I stop eels from eating my other fish?

Keep predatory eels in an isolated tank. Eels are strict carnivores and will consume juvenile Tilapia or small tank mates if they share the same enclosure, especially if the automated feed dispenser runs empty.

What is the most profitable fish to raise in Probably Stolen?

For passive, continuous profit, Common Tilapia is the most reliable due to its fast 8-day adult cycle and self-sustaining 15% nightly breeding rate. For raw credit value per item, Sturgeon and specialty products like Caviar and Medicinal Eel skins fetch the highest per-unit payouts from luxury traders and black market fences.