Name: Epalzeorhynchos frenatum
Origin: Thailand (Mekong R.)
The Epalzeorhynchos frenatum (formerly Labeo frenatus and often misspelled as Epalzeorhynchus frenatus) is a very beautiful and active fish, spending most of the day nibbling everything in search of algae and bits of food, which it finds using 2 pairs of sensitive barbels beside the mouth. They have a brown body with a whitish belly, red fins, and a small dark stripe which crosses the eyes. The colors are all attractively bright and solid on healthy specimens. It's quite an undemanding fish and generally easy to keep. But it is known to be intolerant towards others of the same family, so most books recommend keeping a single specimen in a community tank. It readily accepts all kinds of food, but they should be offered in little pieces because its mouth is pretty small.
Red finned sharks are also commonly known as rainbow sharks, and many pet stores commonly have them labeled as such. I have found with the two that I have had, one when I was in middle school and the present one that I have now 16 years later, that they tend to be loners. My rainbow shark keeps to himself and is seen only a few times a day, hiding or just tucked away at the back of the aquarium. I have also witnessed red fin/ rainbows getting very large. One store in Houston had one in a cichlid tank and was 6-8 inches in length. One last tip, if you have large seashells with openings that a fish could swim in, fill it with gravel. That is how I lost my first rainbow shark.
I have tried to find information on this beautiful fish, and have been somewhat unsuccessful. But an interesting tidbit of information I did find was the misspelling of it's name. The correct spelling is Epalzeorhynchos frenatum, as defined at the Fishbase website. Anyway, my fish's name is still Frenatus because it is too late to change his name now. I have had him for two years and he has grown to five or so inches and is quite the bully (I had to purchase him his own tank, where he lives with a large pleco).
Red-Finned Shark Disambiguation: the scientific name of the Red-Finned Shark is usually given as Epalzeorhynchos frenatum. However, another member of the Epalzeorhynchos genus is very commonly offered for sale as E. frenatum, E. munense, which is very similar in appearance. While in a general sense this is not important, as care and behavior are identical, there is one minor differentiation: the front base of the dorsal fin in E. frenatum is even with the pectoral fins, while in E. munense it starts just in front of the pectoral fins. Both fish are known as the Rainbow/Red-Finned Shark.
One other note about the Red-fin Shark is that it is a JUMPER. Cover every little opening in the lid of the tank because it will find them and jump out. My red-fin jumped out of the small opening in the top of the tank for the filter twice within the first six hours I bought him. The second time he jumped out I had to resuscitate him because he had been out of the tank for way too long.
The body color of this elegant fish may vary towards a slate gray, its fins towards a lacquer red to brick red. Its new fancy name "Rainbow Shark" is misleadingly ambitious, but its earlier name "Bridled Labeo" translated the Latin species name and drew attention to its subtle marking. This Epalzeorhyncus is less aggressive than E. bicolor. A trick that worked for me was to keep three, not two, in a densely-planted tank with roots and hollow logs. There were five or six desirable hideouts and the three, well-matched in size, settled in with a good deal of competitive display and feinting, but no torn fins. When I lost one, though, the other two began to square off and had to be separated in the end. I believe most of the "Labeos" we buy or see are still sexually immature.