Common Name- The Knife Livebearer
Water Conditions- Not Critical. Temp
74-82, Some water movement,
Behavior- A Very peaceful community
Breeding- Separate gravid females into
separate tank. May eat fry.
10-30 Young after approx.30 days.
Size- Females- 3.5 inches, Males- 3.0
This fish occupies the upper level of the aquarium, adapted
to feeding on insects from the surface just above them. These
hardy, and seem to adapt to most conditions. From streams and
moving water, they require some water movement and aeration.
perfectly peaceful, and do not bother other tankmates, though
they can be picked upon. This is a beautiful yellow fish, very
sleek and active
with soft, subtle markings. On occasion this line has
produced leucistic individuals that are more a curiosity than a
viably attractive mutation.
There have been about 20, but they have all been male and
unwilling to breed. Their eyes were not blue, but silver with
black irises on an
ivory or light amber colored body.
Keeping them in a tank that provides room to swim. 2-3 young
pairs can be kept and will do well in a 10 gallon aquarium.
Older females can
get fairly large, at up to about 3 inches, and you may find
with a community of them that 20 gallons is a minimum tank size
for this species.
Our colony of breeders is kept in a 50 gallon bare bottom
tank with a bottom layer of Java fern
filling up the bottom third of the aquarium (See
Plants page). They are fed dry foods
primarily, and they do very well when a culture of fruit flies
is kept for them. Otherwise they will take all
other types of live foods,
but generally do not feed off the bottom of the aquarium. They
will eat fry
inconsistently- here they do, and females
are given their own tank to drop their fry, and the fry are
raised separately. Others I know who are keeping the same line
of fish have tanks
full of the smallest young seeming to swim comfortably with
the parents. A combination of diet and water quality differences
accounts for this. Your ability to raise a large group of
them will depend on your removing the gravid females, and then
raising the fragile,
small young on their own.
For some who keep this species they encounter an initial sex
ratio imbalance where broods will be predominantly male or
female. In the
instances where this has occurred, in my experience, the
ratios evened out by the third generation.
Here, these are a species that breeds seasonally. This
fishroom is exposed to windows with
light from outdoors,
and the room cools in the
wintertime. As a result, these generally do not drop any fry
from about September to Mid-March.
Females become large and “stuffed” in appearance with a
narrow black outlining of the gravid area when she is about to
Sometimes a true black gravid spot is never really visible,
her size being the only indication she is about to drop. Young
sometimes be kept in a net breeder, but generally they are
too large and must be placed into a 5 or 10 gallon tank of her
own with a
moderate amount of plants. The
young do not hide in the
plants, however, and will school in a tight group together just
surface. They are elongated, transparent, and barely visible,
with a length of about 6mm. Broods average from 10 to 40 young.
Provided with reasonably clean water, a tank with room to
swim, aeration and quality foods, these will do very well for