The Alien Containment unit is one of the most fascinating features in Subnautica 2. It lets you capture, study, and breed the planet's diverse marine life inside your own base. From tiny peepers to massive predators, you can build a living museum of 4546B's ecosystems -- if you know how to set it up properly.
The Alien Containment is a large cylindrical tank that fits inside a Multipurpose Room. It holds up to 10 creatures (or eggs) at a time, though different species have different space requirements. Small fish like peepers and bladderfish count as 1 each, while larger predators can take up 3-5 slots. If you overcrowd the tank, creatures stop breeding and may become aggressive.
Alien Containment Specs
| Property | Value | Notes |
|---|---|---|
| Size Required | 1 Multipurpose Room | Floor to ceiling |
| Capacity | 10 "units" of creatures | Large creatures take more slots |
| Power Draw | 1 p/min | Very low consumption |
| Build Cost | 3x Titanium, 2x Glass, 1x Wiring Kit | Requires blueprint |
| Max Stack Height | 2 units (multi-floor) | Stack vertically for more space |
One of the best features is that you can stack Alien Containment units vertically. If you have a two-story Multipurpose Room, you can build two containment units that connect internally, creating one tall tank. This doubles your capacity and allows for more diverse ecosystems. Stacked units count as one shared habitat for breeding purposes.
To unlock the Alien Containment blueprint, you need to find its data box in the Grassy Plateaus wreck or scan fragments in the Kelp Forest caves. Most players find it by accident while exploring early wrecks, but if you are specifically looking for it, check the larger wreck sections in the 100-150m depth range.
Alien Containment Facility Overview
The Alien Containment unit is one of the most fascinating features in Subnautica 2. It lets you capture, study, and breed the planet's diverse marine life inside your own base. From tiny peepers to massive predators, you can build a living museum of 4546B's ecosystems -- if you know how to set it up properly.
The Alien Containment is a large cylindrical tank that fits inside a Multipurpose Room. It holds up to 10 creatures (or eggs) at a time, though different species have different space requirements. Small fish like peepers and bladderfish count as 1 each, while larger predators can take up 3-5 slots. If you overcrowd the tank, creatures stop breeding and may become aggressive.
Alien Containment Specs
| Property | Value | Notes |
|---|---|---|
| Size Required | 1 Multipurpose Room | Floor to ceiling |
| Capacity | 10 "units" of creatures | Large creatures take more slots |
| Power Draw | 1 p/min | Very low consumption |
| Build Cost | 3x Titanium, 2x Glass, 1x Wiring Kit | Requires blueprint |
| Max Stack Height | 2 units (multi-floor) | Stack vertically for more space |
One of the best features is that you can stack Alien Containment units vertically. If you have a two-story Multipurpose Room, you can build two containment units that connect internally, creating one tall tank. This doubles your capacity and allows for more diverse ecosystems. Stacked units count as one shared habitat for breeding purposes.
To unlock the Alien Containment blueprint, you need to find its data box in the Grassy Plateaus wreck or scan fragments in the Kelp Forest caves. Most players find it by accident while exploring early wrecks, but if you are specifically looking for it, check the larger wreck sections in the 100-150m depth range.
All Egg Locations and Rarity
Eggs are the primary way to populate your Alien Containment. Different species lay eggs in different biomes, and some eggs are extremely rare. Knowing where to look saves you hours of searching. Here is a comprehensive guide to every hatchable egg in the game.
Eggs come in different sizes and colors, and each species has a unique egg appearance. Small eggs (from fish like peepers, garryfish) are easy to miss -- they are about the size of your fist and often tucked into crevices. Larger eggs (from predators like bone sharks and sand sharks) are more obvious but guarded by their parents, making them riskier to collect.
Egg Location Reference Table
| Species | Egg Name | Biome(s) | Depth Range | Rarity |
|---|---|---|---|---|
| Peeper | Peeper Egg | Safe Shallows, Coral Reef | 0-100m | Common |
| Bladderfish | Bladderfish Egg | Safe Shallows, Kelp Forest | 0-150m | Common |
| Garryfish | Garryfish Egg | Grassy Plateaus | 50-200m | Uncommon |
| Sand Shark | Sand Shark Egg | Grassy Plateaus, Sand Dunes | 100-300m | Uncommon |
| Boneshark | Boneshark Egg | Bone Fields, Deep Lilypads | 300-600m | Rare |
| Crabsnake | Crabsnake Egg | Deep Lilypads Caves | 250-400m | Rare |
| Jellyray | Jellyray Egg | Mushroom Forest, Deep Reef | 100-500m | Uncommon |
| Ampeel | Ampeel Egg | Deep Grand Reef | 500-800m | Very Rare |
| Ghost Leviathan | Ghost Leviathan Egg | Lost River / Void Edge | 700-1000m | Extremely Rare |
| Sea Dragon | Dragon Egg | Lava Zone | 1000-1300m | Legendary (3 total in world) |
The rarest eggs -- Ghost Leviathan and Sea Dragon -- are end-game collectibles. There are only a handful of each in the entire game world, and collecting them requires significant preparation. The Dragon Eggs in particular are found only in the Lava Castle and Lava Lakes, guarded by Sea Dragon Leviathans. You have been warned.
To collect an egg, simply swim up to it and pick it up. Eggs go into your inventory and can be placed in the Alien Containment later. They do not expire or degrade, so you can carry them around indefinitely. If you die with eggs in your inventory, they are lost like any other item, so be careful on egg-collecting expeditions.
Hatching Mechanics and Incubation Times
Once you place an egg in the Alien Containment, it will eventually hatch. But "eventually" can mean very different things for different species. Hatching time varies from a few minutes to over an hour of real time, and some eggs have special requirements before they will hatch at all.
Most common fish eggs hatch in 5-15 minutes of real time. Just drop them in the tank, wait, and eventually you will see a baby fish swimming around. The baby will grow to adult size in another 10-20 minutes. Once fully grown, it can breed with other members of its species if there are at least two adults in the tank.
Hatching and Growth Times by Species
| Species | Hatch Time | Growth to Adult | Special Requirements |
|---|---|---|---|
| Peeper | 5 min | 10 min | None |
| Bladderfish | 5 min | 8 min | None |
| Garryfish | 8 min | 12 min | None |
| Sand Shark | 15 min | 20 min | Warm water (above 15C) |
| Boneshark | 20 min | 25 min | Deep tank (2+ units tall) |
| Crabsnake | 25 min | 30 min | Plants in tank required |
| Jellyray | 15 min | 20 min | None |
| Ampeel | 40 min | 45 min | Electric stimulation (build near power) |
| Ghost Leviathan | 60 min | Never grows to full size | Deep dark tank, no lights |
| Sea Dragon | 90 min | Juvenile only | Very high temperature |
Some eggs require specific environmental conditions to hatch. Crabsnake eggs, for example, only hatch if there are plants growing in the containment unit. You can grow table coral or creepvine inside the tank to satisfy this requirement. Ampeel eggs need to be near an active power source -- building your containment unit next to a reactor room dramatically speeds up hatching.
An important note about leviathan eggs: the babies that hatch from Ghost Leviathan and Sea Dragon eggs never grow to their full adult size. They remain as juveniles in the tank, permanently small and non-threatening. This is a good thing -- a full-size Sea Dragon in your base would be catastrophic. The juvenile versions are still impressive display pieces, though.
Creature Compatibility and Tank Population
Not all creatures get along in the Alien Containment. Put predators and prey together, and you will quickly have a tank full of predators (and no prey). Understanding which species can coexist is essential for building a diverse and stable aquarium.
The golden rule is: herbivores and small fish can generally coexist with each other. Predators will eat any smaller fish they share a tank with. Large predators may even fight each other if the tank is too small. For a peaceful community tank, stick exclusively to herbivorous and non-aggressive species.
Creature Compatibility Chart
| Group | Species | Can Coexist With | Avoid In Same Tank |
|---|---|---|---|
| Tiny Herbivores | Peeper, Bladderfish, Reginald, Hoopfish | All herbivores, Jellyray | Any predator |
| Medium Herbivores | Garryfish, Spinefish, Rabbit Ray | Tiny herbivores, each other | Boneshark, Sand Shark |
| Small Predators | Sand Shark, Stalker, Crabsnake | Other small predators (if plenty of space) | Tiny herbivores, each other if crowded |
| Large Predators | Boneshark, Ampeel | Only same species (2 max) | Everything else |
| Leviathan Juveniles | Ghost Leviathan baby, Dragon baby | Nothing else (they eat everything) | All other creatures |
If you want maximum biodiversity, the best approach is to build multiple Alien Containment units in separate rooms. Each tank can have its own ecosystem. A shallow reef tank with peepers and plants. A deep-sea tank with bonesharks and crabsnakes. A predator tank with sand sharks and stalkers. This way, nothing gets eaten, and you can display the full range of 4546B's wildlife.
Population control is also important. Creatures breed continuously if conditions are right, and you can quickly end up with an overcrowded tank. When the tank hits capacity, breeding stops. If you want to keep populations manageable, you can either release excess creatures back into the wild or... well, some species are edible. Fish farming is a valid food production strategy.
Breeding and Population Management
Breeding is where the Alien Containment really shines. Once you have a breeding pair of any species, they will produce eggs on a regular schedule. These eggs can be hatched, eaten, or released into the wild. With a well-managed breeding program, you can produce unlimited fish for food, bait, or just for fun.
Breeding requires at least two adults of the same species in the tank. They will periodically produce an egg (roughly every 15-30 minutes for common species), which you can then move to a separate hatching tank or leave to hatch naturally. The baby fish will grow up and join the breeding population, creating an exponential growth curve until you hit the tank capacity limit.
Breeding Rates by Species
| Species | Time Between Eggs | Eggs Per Pair (lifetime) | Food Value |
|---|---|---|---|
| Peeper | 15 min | Unlimited | 12 food, 10 water |
| Reginald | 18 min | Unlimited | 25 food (best fish) |
| Garryfish | 20 min | Unlimited | 18 food, 5 water |
| Bladderfish | 12 min | Unlimited | 3 food, 30 water (best water) |
| Sand Shark | 35 min | Limited (~10 total) | 30 food (but risky) |
| Boneshark | 45 min | Limited (~6 total) | Not recommended |
For food production, Reginalds and Bladderfish are the MVPs. Reginalds have the highest food value of any common fish (25 points per fish), and they breed quickly. Bladderfish provide both food and water, making them useful for emergency supplies. A single breeding pair of Reginalds can produce enough fish to feed one player indefinitely if you manage the population properly.
The most efficient fish farm setup uses two stacked Alien Containment units (20 capacity total) with 2 adult Reginalds and 2 adult Bladderfish. The Reginalds provide food, the Bladderfish provide water, and their combined breeding rate produces enough offspring to keep you supplied without overcrowding the tank. Harvest the babies regularly and leave the breeding pair intact.
Plant Life in the Containment Unit
An Alien Containment does not have to be just fish. You can also grow various aquatic plants inside the tank, creating a more natural and visually appealing environment. Plants also serve practical purposes: some species provide food, others provide crafting materials, and some are required for certain eggs to hatch.
Planting in the containment unit works differently from exterior grow beds. You place seeds or spores directly into the substrate at the bottom of the tank. Different plants have different space requirements. Creepvine, for example, grows tall and needs a stacked (two-story) tank to reach full size. Table coral is short and spreads horizontally.
Growable Aquatic Plants
| Plant | Seed Type | Growth Time | Uses |
|---|---|---|---|
| Creepvine | Creepvine Seed Cluster | 20 min | Rubber (creepvine sample), decoration |
| Table Coral | Table Coral Sample | 15 min | Computer chips, decoration |
| Marble Melon | Marble Melon Seed | 10 min | Food (fruit) |
| Chinese Potato | Chinese Potato Seed | 8 min | Food (staple crop) |
| Membrain Tree | Membrain Tree Seed | 30 min | Decoration, benzene production |
| Gel Sack | Gel Sack Spore | 12 min | Aerogel material |
Gel Sacks are particularly useful to grow in containment units. They are used to make Aerogel, a crucial late-game material, and having a renewable supply in your base is very convenient. Just plant a few spores in the bottom of the tank and harvest the gel sacks as they grow. Each plant regrows in about 12 minutes.
For the Crabsnake egg hatching requirement (plants in tank), any plant will do. Table coral or gel sacks are easy to grow and satisfy the condition. You do not need a full garden -- even one plant is enough to trigger hatching. The plant just needs to be mature and healthy when the egg is ready to hatch.
Building the Ultimate Aquarium Base
For dedicated collectors, the Alien Containment is more than a single room -- it is an entire base wing dedicated to displaying the wonders of 4546B. Building an aquarium base takes planning, resources, and time, but the result is a stunning living museum that is uniquely yours.
The ultimate aquarium base has multiple themed tanks, each showcasing a different biome or ecosystem. A reef tank with colorful fish and coral. A deep-sea tank with bioluminescent creatures. A predator tank with sharks and other hunters. A rare specimen tank with your most prized finds. Connect them all with glass corridors, and you have a base that doubles as a wildlife park.
Aquarium Base Layout Plan
- Entrance Lobby: Reception area with information displays and lockers
- Shallow Reef Tank (Floor 1): Peepers, Reginalds, Bladderfish, Table Coral
- Kelp Forest Tank (Floor 2): Stalkers, Garryfish, Creepvine (full height)
- Deep Sea Tank (Floor 3): Bonesharks, Crabsnakes, Jellyray, Membrain Trees
- Predator Tank (separate wing): Sand Sharks, Ampeels (carefully managed)
- Rare Specimen Wing: Ghost Leviathan juvenile, Sea Dragon baby (solo tanks)
- Research Lab: Scanner, fabricator, specimen data terminals
Such a base requires significant resources. Each Alien Containment unit costs 3 titanium, 2 glass, and 1 wiring kit. With 8+ tanks, plus corridors, decorations, and life support, you are looking at hundreds of titanium and dozens of advanced materials. Start small and expand over time as you gather more resources and find more species.
One final tip: build your aquarium base in a beautiful location. The whole point is to have something nice to look at. A shallow reef base with lots of natural light coming through glass corridors makes your fish collection look even better. Or go the opposite direction and build deep in the Crystal Caves, where the bioluminescent creatures glow in the dark water. The choice is yours.