A Guide to Discovering the Optimal Fuel for the Bioreactor in Subnautica

Are you searching for information on the best fuel options for bioreactors in Subnautica? If you’re reading this, chances are you’ve been playing the game for a while and know how important it is to have a fully powered base for your survival. Without power, you won’t be able to charge your batteries or replenish your oxygen supply when inside your underwater habitat, which is crucial in the early stages of the game. While the bioreactor isn’t the most powerful power source in Subnautica (that honor goes to the nuclear reactor), it is much more reliable than solar panels, which only work during the day. Using a bioreactor allows you to build your habitat further from the surface, and the fragments needed for it are easy to obtain. However, using the right power source is essential to keeping your base powered up. In this article, we’ll provide you with all the information you need about the bioreactor in Subnautica and the best power sources to use with it. Let’s get started!

Location of Bioreactor Fragments in Subnautica

Before anything else, let’s talk about how to build a bioreactor for your habitat in Subnautica. If you already have one, feel free to skip this section and move on to bioreactor power sources. To build a bioreactor, you’ll need to scan fragments (2) to obtain the blueprint. The good news is that these fragments are relatively easy to find. One good location to search for bioreactor fragments in Subnautica is the “Grassy Plateau” area, located a few hundred meters west of your lifepod. This area is characterized by large stone pillars and red blades of grass covering the seafloor. Just be cautious of Sand Sharks while searching for fragments. Once you’ve collected the fragments, you’ll need the following materials: 3x Titanium Ores, Wiring Kit, and Lubricant. Once you have these materials, use a habitat builder to construct the bioreactor inside your habitat. It can only be built inside a multipurpose room, right in the middle.

Best Bioreactor Power Sources

By now, you should have a bioreactor powering your habitat. As the name suggests, it converts organic matter into usable energy for your base. However, the amount of power it generates depends on the organic matter you use as fuel. It can be frustrating to return to your habitat for a resupply, only to find that everything is powered down due to an ineffective bioreactor. The best fuel sources for a bioreactor in Subnautica are different fish species. The top choice is the Oculus fish. It looks similar to the common Peeper fish, but larger with bioluminescent eyes. One Oculus fish placed in a bioreactor produces 10,080 units of power per load, the highest in the game. However, obtaining these fish can be challenging since they are only found in the Jellyshroom Cave, which is inhabited by aggressive snake-like creatures called Crabsnakes. The Jellyshroom Cave is also quite deep, up to 300 meters, so make sure to bring necessary equipment like a rebreather, an upgraded Seamoth, and a high-capacity oxygen tank. Another benefit of exploring the cave is that you can find blueprints for a multipurpose room. When you progress further in the game, you’ll be able to build an alien containment unit, which allows you to breed Oculus fish within the safety of your base.

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If getting Oculus fish is proving difficult, a more accessible alternative would be to use either a Reginald or a Spadefish. Both species are abundant and easy to find, especially in the Grassy Plateaus. A Reginald fish placed in a bioreactor produces 7,840 units of power per load, while a Spadefish produces 6,720 units of power per load. These are the second and third best fuel sources for your bioreactor. Additionally, they pose no danger while collecting them, as they thrive close to the surface.


That covers everything you need to know about the bioreactor in Subnautica and the best fuel sources to use with it. While using fish as fuel might not be everyone’s cup of tea, in a survival adventure game like Subnautica, you have to make the most of the resources available to you. Using the right fuel will greatly help you progress in the game. If you need help with any other game, be sure to check out our Game Guides for more information.

Updated at 7:06 - 01/08/2023
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