Fire eel care
Mastacembelus erythrotaenia · Lowland Southeast Asia: Thailand, Cambodia, Vietnam, the Malay Peninsula, Sumatra and Borneo
Fire eels are the largest spiny eels, dark with red stripes and spots, and they grow to about 3 feet.
- Tank size
- 180 US gal or larger
- Temperature
- 75 to 82 °F (24 to 28 °C)
- Group size
- Alone or in a pair
- Temperament
- Semi-aggressive
- Adult size
- 39 in (the largest spiny eel; up to about 3¼ ft)
- pH
- 6.5 to 7.5
- Hardness (GH)
- 5 to 15 dGH
- Lifespan
- 10 to 20 years
- Diet
- Carnivore
- Care level
- Demanding
In a 210 gallon
72½ × 24½ × 29⅝ in outsideHow to keep fire eels
Fire eels are the largest spiny eels, dark with red stripes and spots, and they grow to about 3 feet. One needs a tank of 180 gallons or more at 75 to 82 °F with deep, soft sand, hiding pipes and a tight lid.
Diet: Carnivore: live and frozen worms, shrimp, fish pieces. Fish food types compared · how often to feed.
Where they swim: Bottom of the tank.
Fire eel tank mates
Share the temperature and water, and neither side eats, nips or bullies the other. Check the full group in the stocking checker.
Clown knifefish
39 in · 250+ gal · 75–82 °F
Silver arowana
36 in · 250+ gal · 75–82 °F
Bala shark
14 in · 125+ gal · 72–82 °F
Kissing gourami
12 in · 75+ gal · 72–82 °F
Uaru
9.8 in · 75+ gal · 79–86 °F
Blood parrot cichlid
8 in · 55+ gal · 76–80 °F
Severum
8 in · 55+ gal · 75–84 °F
Angelfish
6 in · 29+ gal · 76–84 °F
Keep apart
Neon tetra: Adult fire eels eat fish under about 3 in; neon tetras grow to 1.6 in.
Cardinal tetra: Adult fire eels eat fish under about 3 in; cardinal tetras grow to 1.2 in.
Black neon tetra: Adult fire eels eat fish under about 3 in; black neon tetras grow to 1.5 in.
Green neon tetra: Adult fire eels eat fish under about 3 in; green neon tetras grow to 1 in.
Ember tetra: Adult fire eels eat fish under about 3 in; ember tetras grow to 1.2 in.
Glowlight tetra: Adult fire eels eat fish under about 3 in; glowlight tetras grow to 1.5 in.
What a fire eel tank needs
A tank of 180 US gallons or more (such as the 210 gallon) with a tight lid (they jump), and the equipment below.
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Fluval FX4
Rated by the maker for up to 250 US gal, which covers a 210 gallon fire eel tank without being built for a far bigger one.
Fluval FX6
Rated by the maker for up to 400 US gal, which covers a 210 gallon fire eel tank without being built for a far bigger one.
EHEIM thermocontrol 300
Fire eels need 75 to 82 °F; most homes run cooler, so a heater holds the temperature. Aqueon’s chart gives two 300 W heaters for a 210 gallon tank, and a second heater is worth having here: if one fails, the other keeps the water from going cold. Heating a big tank.
API Freshwater Master Test Kit
Tests ammonia, nitrite, nitrate and pH, the readings that matter most before and after adding fire eels.
Seachem Prime 100 mL
Removes chlorine and chloramine from tap water at every water change.
Fluval Edge Thermometer
Shows the water temperature at a glance, so you know it stays within 75 to 82 °F.
We don’t list fish food: any good brand of the foods under Diet will do. Plan the whole tank's equipment →
Common fire eel problems
- They escape through any gap; cover the tank.
- Small fish are eaten.
- Sharp gravel scratches their skin; use soft sand.
Test the water first whenever fish look unwell: see what your readings mean, then match the symptom. For disease, a vet who treats fish can diagnose it and advise treatment.
More to compare
Sources
Name, origin and adult size checked against Wikipedia: Mastacembelus erythrotaenia. Temperature, pH, hardness, group size, lifespan and minimum tank size are common hobby guidance, not figures from that article. Ranges are the range the species tolerates; aim for the middle. Minimum tank sizes are for an adult group. Drawings are our own; photo credits follow.
Photo credits
Real photographs from Wikimedia Commons, resized and cropped to fit; each is used under the license named.
- Fire eel Llandor, CC BY-SA 3.0, via Wikimedia Commons
- Clown knifefish Parkourprincess, CC BY-SA 4.0, via Wikimedia Commons
- Silver arowana Qwertzy2, CC BY-SA 3.0, via Wikimedia Commons
- Bala shark H. Zell, CC BY-SA 3.0, via Wikimedia Commons
- Kissing gourami 5snake5, CC BY-SA 4.0, via Wikimedia Commons
- Uaru Brent Tibbats, CC BY 3.0, via Wikimedia Commons
- Blood parrot cichlid Citron, CC BY-SA 3.0, via Wikimedia Commons
- Severum Trisha M Shears, Public domain, via Wikimedia Commons
- Angelfish Citron, CC BY-SA 3.0, via Wikimedia Commons
- Neon tetra Holger Krisp, CC BY 3.0, via Wikimedia Commons
- Cardinal tetra CHUCAO, CC BY-SA 3.0, via Wikimedia Commons
- Black neon tetra Debivort, CC BY-SA 3.0, via Wikimedia Commons
- Green neon tetra Sascha Biedermann, CC BY-SA 2.5, via Wikimedia Commons
- Ember tetra Klaus Rudloff, CC BY-SA 4.0, via Wikimedia Commons
- Glowlight tetra gonzalovalenzuela; cropped by Kyknos, CC BY 2.0, via Wikimedia Commons
- Black ghost knifefish Vassil, CC0, via Wikimedia Commons
- Senegal bichir Zhyla at English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons
- Elephantnose fish Jutta234, CC BY-SA 3.0, via Wikimedia Commons
- African butterflyfish Toniher, CC BY-SA 3.0, via Wikimedia Commons
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