Fishes of the genus Brachyraphis originate in Central America where they inhabit principally the Atlantic and Pacific slopes and drainage areas. Brachyraphis means “short needle”, referring to the gonopodium of the male. They are generally a cannibalistic and aggressive fish best kept in a species aquarium.
Brachyraphis roseni is a recently described (1988) species that ranges from southeastern Costa Rica through western Panama. Females reach 7 cm in length while males reach about 5 cm. The dorsal fin on both males and females is orange on the outer half and is banded with black. The female also has orange on the frontal area of the anal fin followed by a black stripe running from the body to the bottom edge of the fin. The male has a black stripe that runs from the body along the top of the gonopodium. Both sexes have seven or eight faint bands running vertically along the anterior portion of the body and the scales are edged in black giving a net-like pattern. The contrasting orange and black markings on this fish make it one of the more colorful wild-type livebearers available.
I acquired two pairs at our annual show auction in September of last year. Both males and females were about 1 inch in length and since then the males have not exceeded that size but the two juvenile females have reached about 5 cm total length. They are housed in a 20-liter aquarium quite full of Java moss but some open area is available for swimming. Filtration is by sponge filter and the water is regular Calgary tap water (240 PPM and 7.8 pH) to which 1mL salt per 2 L of water has been added. The fish receive brine shrimp nauplii and Spirulina flake at each feeding, and occasionally get a treat of white worms. Water changes of about 50% are done every two weeks.
The fish grew and with time I began to look for signs that the females were gravid. I observed the males coming along side the females from behind and to one side almost as though they were trying to sneak up on them. Usually their advances were spurned, sometimes quite aggressively, but on occasion copulation took place. The females became quite full-bodied at the front but never got that squared-off body shape that, in other livebearer species, indicates the imminent drop of fry. I was surprised to see two fry come out of the Java moss one evening at feeding time, not so much by their presence but by their size. They were about 1 cm long and were clearly not newborns.
I began to watch the females more closely because I had not been aware that fry were in the tank but it did me no good. I was never able to predict when fry would appear. One evening, again at feeding time, I saw a few small, newborn fry resting on the bottom of the tank. I collected them into an ice cream bucket and checked the tank every 15 minutes to gather newly dropped fry as they appeared. I’m not entirely clear on what happened that night. Although I looked at both of the females very carefully, I couldn’t tell which one was dropping fry. I gathered 35 free-swimming fry, two belly sliders, and two dead fry so the possibility exists that they were both dropping fry (brood numbers are reported to be around 20) but it seems unlikely.
The fry were set up in a 20-liter tank with the same general conditions as the parents’ but with much less Java moss. After all, I didn’t expect them to eat each other (and they didn’t). They ate brine shrimp voraciously and grew quickly. When they were about 1 month old, I began to include Spirulina flake food into their feedings, which they accepted readily. By two months of age, they were about 3 cm total length but all had the same markings and body shape, namely those of a female. I know that with some fish, the water chemistry can affect the sexual distribution of the fry but wasn’t expecting it in livebearers. It wasn’t until 21/2 months of age that the gonopodium began to develop on the males and they began to slim down to the more characteristic male shape. At 3 months of age, both males and females are about 4 cm long. They eat Spirulina flake exclusively and are hearty eaters.
Their cannibalistic and aggressive tendencies make Brachyraphis roseni somewhat of a specialist’s fish but they are attractive, hardy and quite enjoyable to keep… in a species tank, of course!
Livbearing Fishes by John Dawes, Blandford Publishing, London, England 1991.
A Fishkeeper’s Guide to Livebearing Fishes by Peter W. Scott, Tetra Press 1987.
Livebearing Aquarium Fishes by Kurt Jacobs, 2nd Edition T.F.H. Publications, 1973.