Aquariums are one of Planet Zoo 2's biggest additions, with full aquatic habitats, hero species like sharks and rays, shoals of schooling fish and walk-through tunnels. They're also easier to get wrong than land habitats, so here's the order I build them in.
1. Shape the tank
- Use the aquarium barrier tool (acrylic, with a curve builder). Placing an aquarium barrier over an existing path automatically carves the habitat out of the path, which makes the job far quicker than in the first game.
- Curvy, droplet shapes look more natural than boxes.
- Dig the floor with push and roughen tools, and leave rock arches and channels for fish to swim through.
- Big isn't always better: water area drives filtration demand. Narrow the tank in places or add land islands to keep volume sensible.
2. Add a gate and fill it
Aquariums need a staff/aquarium gate, and the water level must sit above the gate, roughly 2 m above the floor where the gate is. If you need shallow water somewhere (a touch pool, for example), keep the gate area deep and slope the floor up toward the guest side.
Water settings let you tune tint strength (transparency), bubbles, fog, mist and surface ripple, and even change the water colour. See Terrain & Water.
3. Filtration and salinity
- Connect the tank to a filtration network and compare supply vs demand.
- Set salinity: almost all reef and ocean fish need salt water. Every species lists its salinity in the Zoopedia.
- Two filters handled a large open-ocean tank; a deep reef needed shrinking to fit its filter capacity.
4. Temperature and cohabitation
Before mixing species, compare temperature ranges and pick a value inside all of them:
| Species | Range |
|---|---|
| Clown anemonefish | 24–28 °C |
| Palette surgeonfish | 23–28 °C |
| Schooling bannerfish | 24–28 °C |
| Ocellated eagle ray | 24–27 °C |
| Hawksbill turtle | 22–30 °C |
| Blacktip reef shark | 22–28 °C |
| Bluespine unicornfish | 24–29 °C |
| Blue-and-gold fusilier | 21–31 °C |
A reef at 26 °C suits all of these. Also check:
- Thriving relationships: the Zoopedia lists which species live well together. Cownose rays have more than 24.
- Predation: sharks will eat small fish. A "predation occurring" alert means your shoal is lunch.
- Big fish vs shoals: the game treats large fish like sharks, rays and triggerfish as individual animals (sometimes called "hero" species), each with its own needs, just like a land animal. Small schooling fish come as a shoal, a whole group bought together, and mostly just need the right temperature, salt level, safety and clean water. Don't assume a fish is a shoal; clown triggerfish aren't.
5. Decorate the reef
- Start with coral rocks, randomly rotated and stacked. Big rocks low, smaller detailed ones near the top.
- Add coral pieces section by section. Each coral has about three variants.
- Use eel grass (large/medium/small) in the deeper, darker parts.
- Pre-built coral blueprints (search "coral" in blueprints) speed this up enormously.
- Watch plant coverage: corals count as plants, and rays dislike too much.
Paint the floor fine sand for sharks and rays (they also bury in it). Rocks above the waterline are fine; keep living coral below it.
6. Tunnels and viewing
- Aquarium guest gate + tunnel pieces create a walk-through. A 4 m tunnel with only a 2 m decline keeps ramps wheelchair-friendly.
- Pull terrain up under tunnel supports so it doesn't look like it's floating.
- Glass tunnels also work as bridges through land habitats that don't allow walk-throughs.
- Keep guests away from the glass with a trim or a gap. Otherwise they clip into it.
You don't need a full tunnel to give guests an underwater view. A watertight glass window in the side of a pool works for otters, manatees and other swimmers.
7. Lighting
Aquarium lighting can be bright. Turning brightness down to about 25% and spacing up to 75–90 gives a calmer, more realistic tank, and it's kinder to the animals.
Enrichment and thriving
- Suspended bait feeders and forage trays (rays).
- Toys: submarines, bubble jets, hoops, lattice balls (after aquatic toy research).
- Food grade 2 is a common thriving requirement for sharks.
The "blue it out" trick
In big indoor tanks, paint every wall the guests might see through the water in the same blue as the water. It blends into the depth and hides the box. Combine with rocks at the corners and the tank looks bottomless.
Common aquarium bugs
- Boxing: "boxed" means the game has put an animal back in its transport crate, usually because it can't move where it is. Draining a tank boxes every animal in it, so unbox them afterwards. Sharks have been prone to boxing near tunnels; patches have improved this.
- "Gate above water level" / "too steep" when editing a filled tank: box the animals, drain, edit, refill. Check that the whole barrier is selected.
- "Animals less than 1 m from the water level can cause obstructions" when editing water: move them away first.
- Salinity resetting to fresh water after refilling: set it again.