Monday, July 23, 2007

Common Livebearers

Live bearers are often one of the first types of fish people get when starting out in the aquarium hobby. It is exciting to have new baby fish so easily! They are very colorful and active, which draws new hobbyist to them. The livebearers most people start out with belong to the family Poeciliidae.

Poeciliidae is considered a livebearing tooth-carp family. They originate from North, Central and South America. Many have been introduce to nonnative areas. The most commonly available in local fish stores include guppies, mollies and platies. While most livebearers do best in harder water (10 to 30 dH) most are adaptable fish, just needing clean water and a varied diet to do well. These fish are unique in that they do not lay eggs, but instead give birth to live babies. The males possess a specialized anal fin called a Gonopodium that they use to internally fertilize the eggs of the female. The female then carries them inside of her until they are mature. Upon birth the fry are quite large compared to egg layer fry and they can swim right away. In the aquarium they often readily take ground flake food almost immediately. Another interesting aspect of livebearer reproduction is that the females can store sperm for later use. It is said that livebearers can give birth to up to 9 batches of fry from one breeding.

Guppies may be one of the most popular aquarium fish because of their flowing tails and bright colors. Guppies naturally come from northeastern South America and islands off of the northeastern coast. However, because they love to eat mosquito larvae, they have been introduced into many areas. There are many different strains of guppies, they are created by line breeding. Because of this fancy guppies are not as hardy as their wild colored counterparts (called "common guppies"). Common guppies are usually sold as feeder guppies. Guppies are best kept in a 10 gallon tank or larger if you want a group of them. They require clean water and frequent small meals. Because of their long flowing fins many other fish are tempted to nip at them, so choose tank mates carefully. Guppies are usually best kept in groups of 1 male to every 2 or 3 females. However, if you do not want them to breed and just want a fantastic display, a tank full of male guppies only can be done. There may be some occasional fin nipping though. Guppies are tolerant of a wide range of temperatures and water conditions. As long as you keep your water clean guppies should be able to adapt to most pH and hardness ranges. Many people find their guppies do a little bit better with some aquarium salt added to the tank water.

Mollies are also very popular. Many mollies are sensitive to water quality. Mollies can range in size from an inch up to 6 inches. It usually a good idea to keep mollies in slightly larger tanks, starting at 30 gallons. They can be a bit more aggressive than some other fish, not to mention some can get quite large. Mollies are omnivores, but should be fed a lot of plant food. Adding spirulina flakes to their diet, or allowing algae to grow for them to graze on will keep them looking their best. As with the guppies mollies do best in groups of 1 male for every 2 to 3 females.

Platies are perhaps one of the most varied of the livebearers after guppies when it comes to color strains. There are many different varieties of guppies. At any given time at Pet World there may be 10 different types or more. There care is about the same as most other livebearers. Usually reaches sizes of up to 2 inches, they can be kept in 10 gallon tanks or larger. They need clean water, and are very adaptable. Again they do best in groups of 1 male for every 2 to 3 females. They will do fine on regular tropical flake food, but their colors look best if given more variety. Adding spirulina flake and some frozen foods like blood worms and brine shrimp will really make these fish look good!

Swordtails are perhaps one of my favorite out of the common livebearers. The males sport a long extension of their tail that gives these fish their common name. Females are usually rounder and do not have the "sword". Swordtails can get up to 5 inches and come in a variety of colors. It is best to keep these fish in tanks of 20 gallons and up. They do best in the standard male to female ratio of 1 male for every 2 to 3 females. Something that is very interesting about swordtails is that they do change gender with some frequency. When born, all swordtails are female. If at a young age a fish develops into a male, it will stay small in size. If a fish grows as a female and later turns into a male, he will be a large male.

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