Critter of the Week - Weekly Entries

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Critter of the Week 01 - Mastacembelus erythrotaenia



Common Name: Fire Eel

Taxonomy: Phylum - Chordata       (animals with a backbone)
                       
                Class - Actinopterygii   (ray-fin fishes)
               
                Order - Synbranchiformes (swamp eels)
             
                Family - Mastacembelidae  (spiny eels)
     
                Genus - Mastacembelus  (asian/eastern spiny eels)

                Species - Erythrotaenia

Range: Eastern Asia; it has been recorded in Laos, Cambodia, Vietnam, Indonesia, Malaysia, and Thailand.

Habitat: This is a freshwater species occupying slow rivers and streams, floodplains, and other low-current freshwater habitats within their range.

Ecology: This is a large, eel-like fish that can be found lurking in swampy streams, floodplains, and slow-moving rivers in eastern Asia. It grows rather large, with adult sizes often approaching 4 feet in length. The Fire Eel is highly predatory, hunting and devouring any food that is large enough for it to swallow; its underslung, narrow jaws are useful for catching small fish, shrimp, worms and crayfish, and it can burrow into areas of the riverbed with a soft bottom; both to pursue prey and evade predators. They also possess sensory organs near the tip of their jaws to help them sense their prey in murky waters.

This fish, like many others, reproduces via external fertilization; after a male and female pair up to spawn, the female releases eggs which are fertilized by the male, who releases a cloud of sperm onto them.

Notes: This species is sometimes seen for sale as an aquarium fish; its has become more popular amongst serious aquarium hobbyists recently due to some success at spawning them in aquariums. They have shown themselves to be very intelligent fish, often able to recognize their caretakers and becoming tame enough to be hand-fed. They are also caught for food in the countries within their natural range.

Conservation Status: While this species is not currently threatened, others within the family Mastacembelidae are. This may be due to farms encroaching on the watersheds that connect to their rivers, which results in excess nutrients (in the form of nitrates and phospates) entering the water, a process called eutrophication. Eutrophied water loses the oxygen dissolved in it due to bacterial action, and fish die of suffocation. In addition to this, some fish in the order Synbranchiformes live in caves, swampy marshland, and other areas with shallow water; farming requires large amounts of water to be drawn from the surrounding water table, and sometimes these water bodies vanish as the water table falls due to farming practices, killing the fish.

Videos:

Feeding 18-Inch Fire Eel

Fire eel