Alfaro cultratus - To this species page

Common Name- The Knife Livebearer     Water Conditions- Not Critical. Temp 74-82, Some water movement, plants     Behavior- A Very peaceful community fish.     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 inches     This fish occupies the upper level of the aquarium, adapted to feeding on insects from the surface just above them. These are exceptionally     hardy, and seem to adapt to most conditions. From streams and moving water, they require some water movement and aeration. They are     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 most likely     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 drop fry.     Sometimes a true black gravid spot is never really visible, her size being the only indication she is about to drop. Young females can     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 beneath the     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 you.