Pacu

Pacu is a small aquatic critter that spawns in polluted water and spends most of its life floating or flopping around in liquid. It is one of the most useful critters for early food production because it lays at least one egg before dying, has a short lifespan of 25 cycles, and drops 1,000 kcal of Pacu Fillet on death, which cooks into 1,600 kcal of Cooked Seafood at an Electric Grill. Newly hatched and adult Pacu both have a mass of 200 kg, and adult Pacu reach maturity in about 5.5 cycles.

Pacu is a temperature-sensitive critter with multiple variants. The base form is the classic pale green Pacu, while colder and hotter breeding conditions can produce other variants, including Gulp Fish and Tropical Pacu. Variant reproduction is tied to the body temperature of the parent, and the different forms keep the same general feeding and breeding behavior, making Pacu one of the most reliable egg sources in the game.

Wild Pacu are easy to exploit for food because an uncrowded wild Pacu will lay one egg even if it is never fed. That egg inherits the wildness of the parent at the moment it is laid, so a wild parent can produce a wild offspring. If the pool becomes overcrowded when an egg is laid, the Pacu can still become cramped, so moving eggs out of the pool is the cleanest way to keep a wild farm stable. Open Pneumatic Doors along the bottom of a pool, an Automatic Dispenser, a Conveyor Chute, or even a Storage Bin can be used to move eggs out of the water and prevent room penalties from building up.

• Pacu can be captured with a Fish Trap.
• Pacu in a flopping state can also be caught with a Critter Trap.
• Pacu are tamed only by feeding them through a Fish Feeder.
• A newly born tame Pacu can live long enough to lay an egg even if it is not fed, provided it has enough space.
• Feeding a Pacu seeds is often a good alternative to algae, since a Fish Feeder only needs one seed per cycle.

Taming and breeding Pacu is usually done through controlled feeder use. A fed Pacu becomes domesticated over roughly 10 cycles, then begins eating algae or seeds and laying eggs very rapidly, often about one every 1.5 cycles while happy. Because the feeder effect depends on being fed rather than on how much is consumed, automation can limit the amount of algae stored in the feeder and drastically reduce consumption. With careful automation, a single Pacu can be maintained on only a few kilograms of algae per cycle, though it will eventually starve if underfed. Eggs can also be raised from the egg stage, which takes longer but still requires relatively little algae.

Pacu behavior is governed by liquid size and density. They swim only in liquid tiles with enough mass to count as substantial, and each Pacu needs 8 connected liquid tiles to avoid overcrowding. If the liquid is too thin, the critter enters a flopping state instead of swimming. Flopping does not damage Pacu, but it does make them unable to eat until they reach suitable liquid again. This behavior can be used to limit movement for performance reasons or to keep them near a feeder, since Pacu pathing can become expensive in large farms.

Some useful details when building around them:

• Pacu can swim through liquid tiles with at least 35% of the default mass.
• Liquid inside Mesh Tiles and Pneumatic Doors counts toward pool size.
• Wild Pacu can still become cramped if eggs are laid in an overcrowded pool.
• Pacu can have trouble moving through mixed or shallow liquids, which can be used to keep them contained.
• Their short lifespan and high egg output make them excellent for food, but also easy to overproduce if the pool is not controlled.

Pacu is also notable for its variants. Gulp Fish convert polluted water into clean water at a slow rate, but require careful temperature management. Tropical Pacu are the hot variant and provide a decor bonus, making them useful in decorative or temperature-controlled farms.