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This article is considered accurate for the current version (U51-600112). |

Pacu is an aquatic Critter found in pools in the Swamp Biome. They produce Pacu Fillets and Eggs, and their morphs can provide fresh Water or decor bonuses. They can be domesticated.
Behavior[]
Pacu spends its time floating around in the pool of Polluted Water in which it was created. They only produce a single egg before expiring, which occurs in only 25 cycles. These pacific critters can only be captured and moved in an aquatic Fish Trap, which complicates domesticating them early on in the game. Alternatively, their eggs can be sweeped into a storage container in another target location.
Their death provides 1,000 kcal of Pacu Fillet, which can be cooked into 1,600 kcal of Cooked Seafood at an Electric Grill.
Once placed in a pool, feeding from a Fish Feeder will slowly domesticate the Pacu over roughly 10 cycles. Its feeding and reproductive behavior drastically change once domesticated: it begins gorging itself on Algae or seeds, and rapidly laying out eggs (one roughly every 1 1/2 cycles) and defecating. This continues until the pool becomes overcrowded, at which point the Pacu returns to its typical behavior; so a single domesticated Pacu can result in an extremely large population very quickly.
Their room size is calculated based on the amount of liquid tiles around them. Each Pacu requires 8 tiles each to not become overcrowded. Liquid inside and sectioned off by Mesh Tiles and Pneumatic Doors are counted and are treated as one homogeneous pool of liquid with the surrounding liquid.

Despite having a lot of space to itself, the pacu on the left is overcrowded because of the pacus in the right section

The 3 Pacus are happy because the pool size is 6x4, even though physically they are trapped by pneumatic doors in a 1x4 area
Pacu only swims in tiles over 350 kg and have trouble swimming in different liquids. This might make it so the Pacu can't reach the Fish Feeder or can be used to limit Pacu movement. The pathing of Pacu can make a significant game performance impact, so limiting their movement with creative liquid management while keeping them happy may be considered.
Pacu require more than 350 kg of liquid in a tile to swim; below that, the critter is considered to be flopping, and can visibly be seen to flop about on the ground. Even though the description reads "Fish out of water" when the Pacu is flopping, it suffers no health loss from it, being able to essentially flop for its full lifespan.
All Pacu have a mass of 200 kg when hatched and when they reach adulthood. Newly born Pacu have body temperatures which are specific to their variant, resulting in heat creation/deletion.
Variants[]
The Pacu is a temperature sensitive critter with three additional variants. Provided the fish is placed in a pool of the correct temperature, it produces its variants consistently and quickly. They all maintain the Pacu's feeding and breeding behaviors, keeping all four variants tied for the most reliable source of eggs in the game.
Pacu[]
The classic pale green Pacu.
When Pacus hatch and reach adulthood, (which takes about 5.5 cycles,) their temperature is 30 °C.
Tropical Pacu[]
The colorful Tropical Pacu is the most frequently spotted variant morph of the Pacu. They emerge when a Pacu reproduces at a temperature above 35 °C. They provide a +25 decor out to a radius of 5 squares but this decor only penetrates Window Tile.
When Tropical Pacus hatch and reach adulthood, their temperature is 55 °C.
Gulp Fish[]
The blue Gulp Fish is the second variant of the Pacu. They emerge when a Pacu reproduces at a temperature below 5 °C. They also have the drawback of requiring temperature management - too hot and they die off, too cold and the pool they are in starts to freeze. They do, however, convert Polluted Water into Water, at a slow and consistent pace of 200 g/s. A large pool filled with these critters can produce enough fresh water to support a base though water needs to be siphoned off quickly thanks to its higher freezing point than Polluted Water. Alternatively, if the Polluted Water is cold enough the water that the Gulp Fish produces will instantly freeze into Ice, which can be collected and melted.
The water that Gulp Fish produce matches their internal body temperature, which can cause heat creation/deletion depending on a Gulp Fish's temperature relative to the Polluted Water that it takes in.
When Gulp Fish hatch and reach adulthood, their temperature is -12.5 °C.
Pacu Ranching[]
Tamed Pacu[]
A newly-born tame Pacu will live long enough to lay an egg even if not fed, similar to Wild Pacu, provided it has enough space.
It is possible to sustain a single Pacu-breeder via Algae Distiller-Pufts pathway. One Pacu requires 7.5 kg of Algae per cycle. The 7.5 kg of Algae require 22.5 kg of slime per cycle, which can be covered with some excess by 1 tame Puft. This in turn would need 50 kg of Polluted Oxygen per cycle. Off-gassing such an amount from polluted water would require a surface area of around 188 tiles (Puft will require at least 144 tiles on their own to not get overcrowding effects). It can be supplemented by Polluted Oxygen Vents and Morbs, although Morbs' production rates are inconsistent. Pacu can also be fed Seeds, requiring 1 of any seed per cycle. Excess seeds from food crops or a Thimble Reed farm could be all you need to maintain a Pacu farm.
Two consistently-fed Pacus maintain one tame Pokeshell.
Farming is more feasible if you can find a way to heavily optimize the system and reduce the algae consumption. Otherwise it will rapidly deplete your algae reserves. With automation and by limiting the amount stored in the Fish Feeder it is possible to feed a single Pacu only a few kilograms of algae per cycle. The Pacu will eventually starve, but until around age 10 it will live of its internal energy store and continuously lay eggs. After that it will intermittently starve, but still have its reproduction increased for a short time directly after a feeding. The length of the starvation and with that the amount of additional eggs can be adjusted by choosing to feed it more algae. The number of produced eggs is thus less than if fed the maximum, but the far lower amount of algae used makes this an economical tradeoff.
An alternative option is to use seeds in your Fish Feeder, as these can be easily gained from a dedicated farm or just from the passive duplication in your colonies other farms. When making a dedicated farm for the Pacu there are 2 main options, the Balm Lily can work well due to the lack of a fertilizer requirement and so only needs the dupe labor to harvest. As mentioned above, Thimble Reed is a great alternative due to its fast growth speed and minimal requirements.
Wild Pacu[]
The Pacu's short lifespan and relatively large food output makes wild Pacu an easy source of food. It will produce one egg throughout its life even when unfed, while dropping fillets for your Duplicants to eat when they die at no resource costs.
Note that wild Pacu can still become Cramped if they are overcrowded when one lays an egg. This can be avoided by moving the egg into another room. A line of open Pneumatic Doors along the bottom of the pool can rectify this by causing freshly-laid eggs to drop out of the room.
An easy way to move Pacu is to move their eggs instead, via an Automatic Dispenser, a Conveyor Chute or by moving the eggs to a Storage Bin in or near the pool and then unassigning storage from the bin, causing the eggs to drop.
Tips[]
- Wild, uncrowded Pacu will lay an egg when they are 20 cycles old. The parent can die just before the egg hatches.
- An adult, wild Pacu can be tamed in less than 8 cycles and taming from the egg takes under 12 cycles, using as little as 480 kg of Algae.
- Creative automation can be used to tame Pacu using less Algae by limiting the Fish Feeder.
- Eggs retain the wildness of the parent at the time the egg is laid.
- Pacu Fry will only eat once from a Fish Feeder only containing Seeds.