The Cardinal Brachy: Brachyraphis roseni
by Birgit McKinnon, Calgary Aquarium Society
originally published in The Calquarium Volume 40, Number 5, February 1998
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!
REFERENCES
Livebearing 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.
Other aquarium clubs and non-profit organizations can use this, or other articles,
in their own journals or web sites, provided that credit is given to the author, the
Calgary Aquarium Society, and The Calquarium. In the case of a reprint in a hardcopy
publication, two copies of the published work are sent to the Calgary Aquarium Society at
its mailing address. And in the case of a reprint in an Internet publication, a link back
to the original article site must be provided in a prominent location. |