The Red Fin Shark (Epalzeorhynchos munense) is a rare species of cyprinid fish found in the Mekong, Chao Phraya, and Mae Klong rivers basins in Indochina that closely resembles the Rainbow Shark (Epalzeorhynchos frenatum).

The Red Fin Shark was named for the Menam Mun River at Tha Chang, East of Korat in eastern Thailand from where it was first collected, and unlike the Rainbow Shark, it is rare in the aquarium trade and has not been commercially bred in Southeast Asian farms.   Specimens have been recorded from some other tributaries of the middle Mekong in both Thailand and Laos, and may occur in Cambodia as well.

The Red Fin Shark is a benthopelagic species that is usually found among boulders and rocks in flowing rivers and streams for most of the year, but are known to move into seasonally inundated floodplains and forested areas during the rainy seasons.

Red Fin Shark (Epalzeorhynchos munense)

The head, body and anal fin of the Red Fin Shark is black.   They have bright red caudal fin and dorsal fins, and black margins on the red pelvic and pectoral fins.   This species also has 11 to 12 branched dorsal-fin rays, and 26 to 30 gill rakers on anterior side of the first arch.

A local variety found in the Mun/Moon river, a tributary of the Mekong in eastern Thailand, has a brown body with a black dorsal fin edged in white, and a white caudal fin.

The unique combination of a black head, body, and anal fin, red caudal and dorsal fins, and black margins on the pelvic and pectoral fins distinguish the Red Fin Shark from the Rainbow Shark (Epalzeorhynchos frenatum).

The two can also be differentiated by the position of their dorsal and pelvic fins.   In Epalzeorhynchos munense, the dorsal base starts ahead of the pelvic fins. In

Albino Redfin Shark (Epalzeorhynchos munense)

Epalzeorhynchos frenatus, the dorsal base is just about in line with the pelvic fins.

Unfortunately, the two species are cross named in tropical fish keeping shops and unless both fish are in hand, they can be difficult to identify.

Fortunately, both species have the same temperament and grow to about the same size. Both become more aggressive as they grow, and although E. munense grows to a little over 9″ long in the wild, both rarely grow more than 3″ or 4″ long in an aquarium environment.

The Red Fin Shark is antagonistic towards their own kind or fish that are similar in appearance.   They are best kept as a single species, one fish per tank. As juveniles, they can be housed with most peaceful species in a community tank, but as they grow larger, they become highly territorial and are best kept with other, like sized medium aggressive fish.   Barbs, larger gourami, danios, and various SouthEast Asian catfish species are all good candidates.   Avoid mixing them with other shark like looking cyprinids.

The Red Fin Shark is best kept in a moderately planted 55 gallon aquarium with a coarse sand or medium size gravel substrate, some rocks and driftwood for them to hide among, and a good filtration system that provides good circulation and a high dissolved oxygen content to the water.   They prefer subdued lighting, a pH of 6.8-7.5, a constant temperature, and a minimum (less than 10 ppm of nitrate, no ammonia or nitrite) of nitrogenous waste.   A tightly fitting cover is also necessary as these species can be jumpers.

Like most minnows, the Red Fin Shark is an egg scatterer as well as an egg eater.  They have not yet been bred in an aquarium environment but they have reportedly been bred through gonadotropic hormone injection.   After scattering up to several hundred eggs and milt, the pair should immediately removed from their eggs.  Any uneaten fertilized eggs will hatch out in a day or so at 80 F.    The fry are free swimming in another day and can be fed newly hatched brine shrimp and finely ground flake foods.

In the wild, the Red Fin Shark feeds on on phytoplankton and zooplankton.  Being largely herbivorous, they eat copious amounts of algae and vascular aquatic plants by grinding them with their pharyngeal teeth. In an aquarium environment, they should be fed spirulina wafers, algae wafers, sinking pellets and some meaty foods in the form of frozen or freeze dried bloodworms or tubifex.

The Red Fin Shark is a rare find for tropical fish keeping enthusiasts and specimens when available are almost always caught in the wild.   Misidentified specimens are occasionally imported and mixed in with other “shark minnows” as juveniles.

Red Fin Shark (Epalzeorhynchos munense)

Minimum Tank Size: 55 gallons
Care Level: Moderate
Temperament: Semi-aggressive
Aquarium Hardiness: Hardy
Water Conditions: 72-79° F, dH 2-15, pH 6.8-7.5
Max Size: 9″
Color Form: Black, Red
Diet: Omnivore
Compatibility: Single species peaceful community tanks
Origin: Thailand, Laos, Cambodia
Family: Cyprinidae
Life Span: 4-6 years
Aquarist Experience Level: Intermediate