TankBud

Fire eel

Mastacembelus erythrotaenia

Also known as Fire spiny eel

FreshwaterFish

Fire eel (Mastacembelus erythrotaenia)
Llandor · CC BY-SA 3.0

Care at a glance

Temperature
75–82°F
24–28°C
pH
6.0–7.5
Adult size
39.4 in
100 cm
Minimum tank
132 gal
500 L
Temperament
Mostly peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Carnivore
Difficulty
Difficult
Breeding
Hard
Rarity
Common
Family
Mastacembelidae
Origin
Southeast Asia (Thailand, Laos, Cambodia, Vietnam, Malaysia, Indonesia)

Overview

The fire eel is a large, nocturnal fish for a very big tank. It is mostly peaceful, and it is a fish for experienced keepers.

Did you know

The fire eel is not a true eel but a spiny eel, named for the row of short defensive spines along its back. Its long body and pointed snout just give it an eel-like look. That snout works like a flexible probe, sniffing out worms and small prey buried in the sand at night.

Caring for the fire eel

Give the fire eel a tank of at least 132 gal (500 L) once it grows. A soft sand bottom is a must, because it burrows and sharp gravel scrapes its skin and leads to fatal infections. Add caves and bogwood for cover, and fit a tight, gap-free lid, because fire eels can escape.

Keep the water at 75 to 82°F (24 to 28°C) with a pH of 6.0 to 7.5. The fire eel is scaleless and very sensitive to copper, so dose any medication conservatively.

It hides by day and comes out to hunt at night. Feed it after lights out with worms, prawns and other meaty foods.

Keep one per tank, since fire eels are solitary and will not tolerate their own kind. It is big, so house it only with fish too large to be swallowed. Breeding in home aquariums is hard and rarely done.

Good to know

The fire eel, Mastacembelus erythrotaenia, belongs to the spiny eel family Mastacembelidae and is one of its largest members. Most stay around 50 to 60 cm in a tank, though wild fish grow larger. Fire eels are long-lived, often pushing well past a decade with good care. Almost every fish in the trade is wild caught.

In the wild

Fire eels come from slow rivers, floodplains and still backwaters across Southeast Asia, including Thailand, Laos, Cambodia, Vietnam, Malaysia and Indonesia. These are warm, soft-bottomed waters where the fish spend the day buried in the substrate.

Common questions

What size tank does a fire eel need?

A fire eel needs at least 132 gal (500 L). It spends most of its time in the bottom.

What temperature and pH does a fire eel need?

A fire eel is comfortable at 75–82°F (24–28°C) with a pH of 6.0–7.5.

What does a fire eel eat?

A fire eel eats worms, prawns and other meaty foods. Feed it after lights out, since it comes out to hunt at night.

How big does a fire eel get?

An adult fire eel reaches about 39.4 in (100 cm).

Related species