fire eel
fire eel

Fire Eel

The fire eel (Mastacembelus erythrotaenia) is a large freshwater eel found in Cambodia, Indonesia, Laos, Malaysia, Thailand, and Vietnam. The Fire Eel is part of the Mastacembelidae family, also referred to as the Spiny Eel family. Members of this family are not true eels. They are elongated, tropical, freshwater fish that have numerous spines preceding the dorsal fin. The fire eel can grow to a considerable size in the wild with specimens often exceeding 1.2 meters (3.9 ft) in length. However, due to limiting factors in the captive environment they usually reach a maximum of around 55 centimeters (22 in), even in very large aquaria.

Despite its name, the Fire Eel is not a true eel. True eels belong to the order Anguilliformes, while Fire Eels are part of the Mastacembelidae family. The name ‘Fire Eel’ is inspired by the creature’s fiery red and orange coloration, marked with horizontal black stripes along its elongated body that give it a resemblance to a lit fuse.

Fire Eels can grow quite large, reaching lengths of up to 1 meter (3.3 feet), although in home aquariums, they typically grow up to around 60 centimeters (2 feet). This large size coupled with their active burrowing behavior means they require spacious tanks with a soft substrate in which they can burrow and hide.

fire eel

Fire Eel in an aquarium

Keeping a Fire Eel in an aquarium can be a rewarding experience for the experienced aquarist. However, their specific needs and behaviors require careful consideration and planning to ensure they remain healthy and vibrant. Here’s what you need to know about keeping a Fire Eel in your aquarium.

1. Tank Size and Setup

Fire Eels can grow quite large, often reaching up to 60 centimeters (2 feet) in a home aquarium setting, so they require a large tank. A minimum of 125 gallons is often recommended, although larger is better. The tank should be equipped with a tight-fitting lid as Fire Eels are known to be skilled escape artists.

The substrate in the tank should be soft, such as sand or fine gravel, to allow for the eel’s burrowing behavior. Sharp or rough substrate can harm the eel’s skin. The tank should also include plenty of hiding spots such as caves, driftwood, or dense plants, which will provide the Fire Eel with the shelter it needs to feel secure.

2. Water Conditions

Fire Eels are tropical freshwater fish and they prefer a pH between 6.0 and 7.5 and a temperature range of 24 to 28 degrees Celsius (75-82°F). They are sensitive to water quality, so a good filtration system is crucial to remove waste and prevent the build-up of harmful substances. Regular water changes are also important.

3. Diet

Fire Eels are carnivorous and their diet primarily consists of invertebrates, small fish, and worms. In an aquarium setting, they can be fed a variety of live or frozen foods such as bloodworms, brine shrimp, or krill. They may also accept high-quality pellets designed for carnivorous fish. Feeding should typically take place in the evening, as they are nocturnal.

4. Tank Mates

While mostly peaceful, Fire Eels can be aggressive towards smaller fish and might eat them. Suitable tank mates include other large, peaceful fish. Small, aggressive fish should be avoided as they might nip at the eel’s long tail. Additionally, due to their poor eyesight, Fire Eels may accidentally bite larger fish while seeking food, so tank mates should be chosen with care.

5. Health

Fire Eels are susceptible to most common fish diseases, but with proper care, risks can be mitigated. Regular water testing to maintain optimal water conditions, a good diet, and a stress-free environment can help prevent disease. Any new fish or plants added to the aquarium should be quarantined first to prevent the introduction of pathogens.

Keeping a Fire Eel in an aquarium is not a venture for the novice fish keeper. These fish require specific care and a significant investment in a suitable habitat. However, for those prepared to meet their needs, the Fire Eel’s striking appearance and interesting behaviors make it a fascinating addition to a freshwater aquarium.

Minimum Tank Size: 125 gallons
Care Level: Moderate
Temperament: Semi-aggressive
Water Conditions: 24-28°C or 75-82° F , pH 6.0-7.2
Diet: Carnivore

fire eel4
fire eel3

The Fire Eel is a nighttime predatory fish. Best suited for a larger aquarium, a soft substrate is necessary for this fish. The Fire Eel will often dig in the base and hide; this may uproot plants and rearrange decorations. A tight lid should be used for any long, slender fish, as they will often try to escape from the aquarium. Fire eels typically enjoy hiding during the day, so the tank should be dimly lit and offer plenty of hiding spaces in the form of large chunks of driftwood or PVC pipes. The Fire Eel should be kept with fish of similar size or larger, and will not tolerate its own kind.
A carnivore, live foods such as earthworms and black worms should be fed to the Fire Eel. Fire Eel also will eat fish small enough to fit into its mouth, so choose tankmates wisely. Will also take insect larvae, beef heart, and prawns. Prepared tablet foods as well as krill and ocean plankton may eventually be accepted.


Fire eels are generally peaceful towards tank mates, although they may be aggressive towards conspecifics. Fire eel tank mate with an Arowana, tire track eel, peacock eel, Siamese tiger, and silver dollars.

Fire eels are long-lived fish in comparison to many of the other types of pet fish. The average lifespan of a Fire eel is about 20 years.

some additional tips for keeping fire eels in aquariums:

  • Provide plenty of hiding places for your fire eel. They like to burrow in the substrate, so you can use sand or gravel as a substrate.
  • Keep the water quality in your aquarium high. Fire eels are sensitive to water quality, so you need to make sure that the water is clean and free of ammonia and nitrites.
  • Feed your fire eel a varied diet. They need to be fed a diet of live or frozen fish, shrimp, and worms.
  • Be patient. Fire eels can be shy at first, but they will eventually come out and explore their aquarium.

By fishexp