The drape fin-barb (Oreichthys crenuchoides) has been sporadically available in the aquarium hobby since at least 2001, when it was known under that common name and, being still undescribed at the time, Oreichthys spp. I had the privilege of keeping a pair back then and, after a period of unavailability, recently purchased a male and two females from my local fish retailer.
These are strange barbs that break the typical barb mold. They are somewhat similar to the sailfin tetra (Crenuchus spilurus) with their calmer activity levels, their overall visual pattern, and the large, robust head and mouth of the male. At the same time, the drape fin barb’s display and combat behavior (and, oddly enough, the sailfin tetra’s reproductive behavior) have been described as cichlid-like – how odd a fish!
Though the specimens currently available are wild caught, I have found this species easy to maintain. This fish does not require any special water preparation and readily accepts flake food. I have kept a wide variety of fish for 25 years as a hobbyist and professional aquarist, and this fish has turned out to be one of my favorites to keep. Its easy, drifting swimming style, clean lines, scalloped scales, and coloration are appealing to view.
This species rarely develops annoying behavioral traits, such as nervous pacing, begging, skittishness, or aggressiveness toward tankmates, and it has the added bonus of exhibiting highly interesting display behaviors. Be forewarned; this species is an efficient and skilled microinvertebrate and fish fry predator. It acts unhurried and seems aloof, which is decidedly charming, but it is extremely accurate and efficient at making livebearer fry disappear. Additionally, it is a pussycat, but not a pushover, with all other piscine tankmates.
A schooling species, even as few as two individuals will show a tendency to stay together. It appears that a level of social organization develops. Males as well as females establish social hierarchies within their sex group. Males, especially, will violently battle each other via mouth locking and pecking combat until one submits.
Once a social hierarchy is formed, the group generally coexists harmoniously. During such confrontational and courtship interactions, mature males erect their very large, sail-like dorsal fins, which are nearly the size of their bodies. Otherwise, the majority of the time, the male’s large dorsal fin is held tightly closed, in drape-like fashion, along the fish’s dorsal surface.
The most exciting feature of this species is, undeniably, the male’s dorsal fin, which I must give special attention to. Before seeing it extended, the fin could easily be overlooked or discounted as not being very special, but once witnessed, the species’ appeal goes way up to something exceptional.
When folded, it does not look very appealing, just a downward-curving sickle of a dorsal fin lying along the dorsal midline and, at times, draping down over one side of the caudal peduncle. In fact, it looks malformed when folded in this position. This is likely the reason this species is called the drape fin barb and not the sail fin barb, as the fish are most commonly seen with this slender drape of a dorsal fin and less commonly seen with it open. In the folded position, a little black, gray, and some light yellow can be seen on the fin, but it is hard to see much.
When on display, the male’s dorsal fin is explosively opened into a roundish glittering and iridescent sail. One can see its subtle coloration and high level of detail in blacks, grays, pastel yellows, and golds, though the fin is less intense in color compared to the female’s saturated lemon yellow and jet-black triangular dorsal fin.
The first few rays of the male’s dorsal fin are curved back and rigid, forming a rounded leading edge, but the remainder of the fin appears to be flowing with less rigidness. A study in subtle beauty, what it lacks in bold colors it makes up for with sheer size, intricate lace patterning, and iridescent coloring. Though I had a male and two females, often days went by where I never saw the male extend his dorsal fin. The unpredictability with which the male’s dorsal fin was displayed made him all the more intriguing.
The male and female’s caudal and pectoral fins are transparent. The female’s pelvic and anal fins are similarly clear, whereas the male’s anal fin is a very subtle shade of translucent rose and the Pelvic fins are translucent yellow. Both sexes have silver scales and a black spot on the caudal peduncle. When displaying to one another both sexes’ color pattern changes; the head and anterior of the body becomes darker gray, the central body portion stays light, and all scales following this lighter area obtain a black border, giving a beautiful scalloped effect.
Noticeable difference between the sexes include a subtle, light-yellow wash to the anterior portion of the body in males and jet-black pigment on the upper half of the iris in females. Males also feature larger heads and mouths. To find out more, you can check out Drape Fin Barb.