Every edible fish in Subnautica: nutrition values, best food fish, bioreactor fuel ranking, breeding with alien containment and the largest creatures.
Subnautica Fish Guide — Every Edible Fish, Best Food and Bioreactor Fuel
Subnautica's ocean is full of fish, but only about a dozen matter for survival. Reginald is the best food in the game (cooked and cured Reginald have the highest food value of any fauna), Bladderfish are the water source, and Oculus is the best Bioreactor fuel in the entire game at 630 energy per slot. This guide lists every edible species with its raw nutrition, explains cooking and breeding, and answers the two questions everyone asks — what the biggest creature in the game is (the Sea Emperor, 160–200 m) and whether the Shadow Leviathan appears in the original Subnautica (it doesn't — it's Below Zero).
Here's what you'll learn:
- Every edible fish with raw food/water values
- Which fish to cook, which to cure, and which to breed
- The full bioreactor fuel ranking with numbers
- How Alien Containment breeding solves food forever
- The largest creatures in the game, ranked by size
Official resources: Steam store page · Official Subnautica Wiki — Peeper · Official Subnautica Wiki — Bioreactor · IGN Subnautica page · Wikipedia — Subnautica
Per the official Subnautica Wiki: "Cooked and cured Reginald have the highest food value of any fauna, making them an excellent food source." The Reginald's scanner entry describes it as a "small, edible prey fish" with a "high calorie count."
Every Edible Fish (Raw Values)
Raw values from the official wiki's infoboxes — note that every raw fish costs water to eat, which is why cooking/curing matters:
| Fish | Raw food | Raw water | Where it lives | Notes |
|---|---|---|---|---|
| Reginald | +25 | -10 | Crag Field, Crash Zone, Grand Reef, Grassy Plateaus, Mushroom Forest | Best food in the game when cooked/cured |
| Peeper | +12 | -7 | Everywhere shallow | The classic starter food; above-average cooked food |
| Magmarang | +12 | -3 | Inactive Lava Zone / Lava Lakes | Lava-zone rations |
| Oculus | +11 | -7 | Jellyshroom Cave | Best bioreactor fuel (630) |
| Eyeye | +10 | 0 | Reef shallows | Zero water cost raw |
| Boomerang | +8 | -3 | Shallows, Kelp | Cheap early snack |
| Spadefish | +8 | -6 | Grand Reef, deeper | — |
| Hoverfish | +8 | -9 | Shallows | Better kept as a pet |
| Holefish | +8 | -5 | Bulb Zone | — |
| Bladderfish | +6 | -4 | Shallows | Do not eat — turn into Filtered Water |
| Garryfish | +4 | -3 | Kelp Forest | Slow, easy catch |
| Hoopfish | +4 | -1 | Sparse Reef | — |
Cooking and curing: the Fabricator turns raw fish into cooked (+food, removes the water penalty) and cooked + salt into cured (better shelf life, more food). Reginald is the top of both piles. The practical early-game chain: Peeper for the first hours, then a Reginald farm once you find a Grand Reef or Grassy Plateaus population.
Bladderfish are worth more as water than food: the Fabricator converts one into Filtered Water (+30 water). Eat them raw and you get +6 food for -4 water — the worst trade in the game. Salt + Bladderfish even makes Disinfected Water. Fish for water, not for snacks.
The Best Food Strategy: Breeding Reginalds
The endgame of Subnautica food is the Alien Containment — a tank in your Multipurpose Room that breeds fish from eggs (or from fish placed inside). The loop:
- Collect Reginald eggs from the Grand Reef/Grassy Plateaus populations (or drop two Reginalds in the tank — they breed).
- Wait for the tank to fill; harvest a few at a time (the tank caps its population).
- Cook or cure the overflow in the Fabricator; throw the rest into the Bioreactor.
Two Reginalds in a tank is a permanent food + fuel + water-adjacent supply. The same tank breeds Oculus for the Bioreactor — the two fish solve survival and base power in one machine.
Bioreactor Fuel Ranking (Fish)
From the official wiki's energy table — fish are the best fuel per slot:
| Fish | Energy | Verdict |
|---|---|---|
| Oculus | 630 | Best energy-per-slot of any item in the game — the wiki says so explicitly |
| Reginald | 490 | The food-and-fuel double duty pick |
| Peeper / Garryfish / Eyeye / Spadefish / Rabbit Ray | 420 | Standard mid-tier fuel |
| Boomerang / Holefish / Magmarang | 280 | Fine in a pinch |
| Bladderfish / Hoopfish / Spinefish | 210 | Wasteful — use them for water or food instead |
| Hoverfish | 350 | Only if you have zero attachment to your pet |
The Oculus wins because it's common in the Jellyshroom Caves, breeds fast in a containment tank, and burns at 630 — a tank of Oculus turns any base into self-sustaining power. Ghost weed seeds (70) and plant seeds are the alternative for players who don't want to breed fish; the full plant-fuel table is in our ghost weed guide.
What Is the Largest Creature in Subnautica?
The leviathan size table, from the official wiki's fauna pages:
| Creature | Length | Notes |
|---|---|---|
| Sea Emperor Leviathan | 160–200 m | The largest living creature in the crater — "the largest known living Leviathan class fauna" per the wiki |
| Sea Dragon Leviathan | 112 m | The lava-zone apex predator; health 5,000 |
| Ghost Leviathan (adult) | 107 m | Lost River + Void guardian; health 8,000 |
| Reaper Leviathan | 55 m | The Crash Zone/Dunes classic; health 5,000 |
| Reefback Leviathan | ~37 m (length unlisted; health 10,000) | Peaceful — the floating island-carrying giants |
| Shadow Leviathan (Below Zero) | 60 m | Below Zero's deep hunter — not in the original game |
So the honest answer to "largest creature in subnautica": the Sea Emperor Leviathan at 160–200 meters wins outright, though you only meet it late in the story. Among the free-roaming predators you'll actually fight, it's the Sea Dragon (112 m). The Shadow Leviathan is Below Zero content — 60 m, found in the Crystal Caves, and covered by our Below Zero map guide if you're playing that game.
"Fish" in the survival sense means the catchable, edible species; leviathans are fauna you can't catch or cook. The distinction matters for the Alien Containment: you can hatch leviathan eggs (Reaper, Reefback, Ghost, Crabsquid) in a tank, but you can't eat the results.
FAQ
What is the best fish to eat in Subnautica?
Reginald — cooked and cured Reginald have the highest food value of any fauna in the game. Find them in the Crag Field, Crash Zone, Grand Reef, Grassy Plateaus and Mushroom Forest.
Which fish should I breed in an Alien Containment?
Reginald for food and Oculus for bioreactor fuel. Two of either breed into a permanent supply; Oculus also happens to be the best fuel-per-slot item in the game (630 energy).
What is the best bioreactor fish fuel?
Oculus at 630 energy per slot. Reginald (490) is second and does double duty as food. Avoid burning Bladderfish or Hoopfish (210) — they're worth more as water and food respectively.
What is the largest creature in Subnautica?
The Sea Emperor Leviathan at 160–200 meters — the largest known living leviathan class fauna in the crater. Among wild predators, the Sea Dragon (112 m) is the biggest. The Shadow Leviathan (60 m) is Below Zero content, not in the original game.
Is the Shadow Leviathan in the original Subnautica?
No — the Shadow Leviathan only appears in Subnautica: Below Zero (Crystal Caves, 60 m long). The original game's deep dangers are the Reaper, Ghost and Sea Dragon Leviathans.
Related Guides
- Subnautica Multipurpose Room Guide — Blueprint, Building and Power
- Subnautica Ghost Weed Guide — Where to Find It and Its Uses
- Subnautica Below Zero Map — Biomes, Coordinates & Navigation
- Subnautica Warper Guide — Where They Spawn and How to Survive
- Rust Beginners Guide — Surviving Your First Week
Last updated: August 13, 2026.
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