Knife livebearer facts for kids
The knife livebearer (its scientific name is Alfaro cultratus) is a type of tropical freshwater fish. It belongs to the Poeciliidae family, which includes many popular aquarium fish. This fish comes from Central America and is often kept as a pet in home aquariums.
Quick facts for kids Knife livebearer |
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About Its Name
The scientific name, Alfaro cultratus, honors a scientist from Costa Rica named Anastasio Alfaro. The common name, knife livebearer, comes from a cool feature on the fish. It has two rows of scales near its tail that look like tiny knives! In Costa Rica, this fish and others like it are often called olomina.
What Does It Look Like?
The knife livebearer has special knife-shaped scales along the bottom edge of its caudal peduncle (the narrow part before the tail). Its body is mostly olive-gray, with a lighter belly. Its sides can have pretty blue or green colors. The fins are clear, but as the fish gets older, its caudal fin (tail fin) gets a dark edge. Male knife livebearers can grow up to 7.5 cm (about 3 inches) long, while females can reach 8.0 cm (about 3.1 inches).
Where Do They Live?
This fish is native to Central America. You can find it in Costa Rica, Panama, and Nicaragua. Knife livebearers usually live in small groups. They prefer slow or moderately flowing creeks and ditches. You can also spot them along the edges of big rivers. Even though they like calmer waters, they are strong swimmers. They have even been found in fast-flowing streams in rainforests! In the Maquenque National Wildlife Refuge in Costa Rica, they are the most common type of poeciliid fish in the rivers.
What Do They Eat?
Knife livebearers are insectivorous, meaning they eat insects. When they are young, they mostly eat aquatic insects (bugs that live in water). As they grow into adults, they switch to eating insects that live on land.
Reproduction and Life Cycle
Like most American poeciliids, knife livebearers reproduce in a special way called ovoviviparously. This means the mother carries the eggs inside her body until they hatch. After about 24 days, the female gives birth to live young. She usually has 10 to 30 babies at a time, sometimes a few more. For a livebearer fish, this is a fairly short pregnancy, and the number of babies is quite small. The young fish grow up quickly and can have their own babies within six months.
Keeping Knife Livebearers as Pets
The knife livebearer is a popular choice for people who enjoy fishkeeping. If you want to keep these fish, they need water that is between 24°C (75°F) and 28°C (82°F). They don't like dirty or still water and can get sick easily. So, it's important to change about 30% of their aquarium water twice a month. Adding aquatic plants to their tank can help them feel less shy and more comfortable.
It's best to keep knife livebearers in an aquarium with only their own kind. Adult fish should be fed small live foods like daphnia. They will also eat flake food. Baby knife livebearers can be fed brine shrimp nauplii (tiny baby brine shrimp).
See also
In Spanish: Alfaro cultratus para niños
