What's the best tank set up for keeping a Fire eel (Mastacembelus erythrotaenia)? Dr Heok Hee Ng advises on how to provide the right conditions for these giant fish.
The Fire eel (Mastacembelus erythrotaenia) is one of the largest spiny eels to be encountered in the aquarium trade, reaching a maximum size of 80cm/32”. Sizes of 1m/40” or more have been reported in the aquarium literature, although these remain unverified.
Captive fish are unlikely to grow this big and usually reach about two-thirds this size in the aquarium. But even a Fire eel at 50cm/20” is a bruiser of a fish, so a minimum tank size of 400 l/88 gal (approximately 120 x 60 x 60cm/48 x 24 x 24”) is highly recommended for one.
Spiny 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.
Many spiny eels show a tendency to burrow and Fire eels are no exception. For this reason, it is best to keep rooted aquatic plants in the tank to a minimum, or to dispense with them altogether.
As with other spiny eels, Fire eels are great escape artists, so a tight-fitting tank cover is a necessity.
Because Fire eels are typically found in large lowland rivers, they are less demanding with regards to water chemistry compared to some of the more habitat-specific species, such as Macrognathus circumcinctus.
A temperature of about 24-28°C/75-82°F, and a pH of about 6.0-7.5 is just about right. The water should be slightly hard at 6-12 GH.
Fire eels are generally peaceful towards tank mates, although they may be aggressive towards conspecifics.
Conventional wisdom dictates that one fish per tank works best, and that peaceful tank mates that are too large to be eaten, like medium to large barbs, are ideal.
Fire eels are ominivorous, although they most readily take meaty foods in the aquarium.
Younger fish can be fed both live and frozen bloodworms, brineshrimp and other invertebrates. Older fish can learn to take larger food items, such as earthworms, chopped or live shrimp and pieces of fish and mussels.
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