Livebearing fish are some of the most common to have in a home aquarium. What makes these fish so unique? They are one of the few species of that are sexually dimporhic and have courtship behavior. Learn more...

Live-bearers are some of the most common fish to have in a home aquarium. Some popular live-bearers include but are not limited to guppies, mollies and platys.

Live bearers are fish that are born almost fully developed, and are called fry when first born. Some fish lay eggs that are fertilized by the male, and the live-bearers actually copulate. They are routinely sold at pet stores and they are usually tank-bred fish. Thus explains some of the unique colors and strains that you see in the pet stores. Fish caught in the wild are rarely seen in pet stores in part because the countries where live-bearers are found are not involved in exporting fish.

A unique feature of live-bearers is that many are sexually dimorphic. Sexually dimorphic means that you can tell the sex of the fish just from looking at it: the males and females have distinct features. In Guppies, the male is "prettier" than the female. The male is characterized by vibrant colors, especially in the tail region; that tail is fan-like in appearance. The female is very drab in color, usually brown. The tail of the female is very short and does not fan out like the male guppy.

In the Swordtail, the male has a pointy long anal fin that is modified as the gonopodium, which is the sexual organ used by fish to copulate. The female is characterized by the absence of this anal fin. When purchasing live-bearers, you are thus usually able to identify the sex.

Live-bearers are social among the fish world and do better in groups of three or more. There is a hierarchy that is established within the school. The dominant male generally has more colors than the other fish. The dominant male is usually first to eat among the school.

Behaviorally, live-bearers are generally non-aggressive towards each other. This comes with an exception of course: the male swordtails can be aggressive towards each other so it is best to keep one male swordtail with several females, rather than multiple males, to prevent fighting.

Live-bearers also demonstrate courtship behavior, a rarity among fish. This behavior can vary among live-bearers. In many species such as the guppies and swordtails, the male swims back and forth rapidly in front of the female, bending his body towards her. This can often lead towards the next step, copulation.

Copulation occurs the same way in most of the live-bearing species. In copulation, the male swims alongside the female and fertilizes her with his anal fin. As mentioned before, the anal fin serves as the copulatory organ, the gonopodium. The male briefly introduces his gonopodium into the pore of the female. One out of ten attempts is usually successful. Interestingly, the female body has the ability to store male sperm for future fertilizations. Females are thus able to have several young after just one mating.

If the female is not interested in mating, she attempts to get away from the male. This is why it is important to have hiding places such as rocks or caves in your aquarium. If the male pursues a female so aggressively that he injures her you will have to remove the female from the aquarium.

After copulation, the female will incubate the fertilized eggs for a period of time which varies from specie to specie. At birth, the young of all live-bearers are fully formed.

Setting an aquarium up for live-bearers is much the same as setting up an aquarium for other fish. It is important to set up the aquarium with all compatible fish. If you are doubt which fish will be compatible, ask before you buy.

The pH for live-bearers should be between 6.5 and 8.0. There are products available that can regulate the pH. As with all tropical fish, live-bearers need a heater to keep their water temperature at about 70-72 degrees.

Live-bearers have a varied diet. They can eat a dry form of food such as flake or tablet form, which is the easiest way to feed your fish. A tropical mix lake food is fine for your live-bearers. Be cautious in feeding pellets; a fish that was not raised or pellets will tend not to eat them later in life. Feed your fish an amount which they can eat in a few minutes. Live food can also be part of the diet of live-bearers. This can come in the form of freeze dried food such as frozen bloodworms or shrimp. You should feed the adult fish twice a day, and should try to feed live food once a week.

Some people obtain live-bearers because they are the easiest fish to breed. Pregnancy in females is easy to detect before feeding. Pregnant females have rounder bellies, and sometimes you can even see the silvery eyes of the fry before they are born. If this is the case, it is time to move the mother to a breeding tank. This can be a separate holding tank or another apparatus that can divide the current tank, separating the male from the female. Gestation lasts about four weeks. If a female is about to give birth and doesnt, it helps to raise the temperature a few degrees. If you do not separate the male and female, the fry will have a minimal chance of surviving because the male will regard them as a midnight snack. When you have fry, it is important to change 25% of the water every week. You will also want to feed more often. There are several commercial fry foods available.

The most common diseases of live-bearers include ick, cotton wool disease, fin rot and intestinal worms. These diseases, when caught in time, can be treated with medications formulated for fish and the specific disease. You can help avoid disease by not introducing visibly sick fish to your tank, removing dead fish immediately, and checking your fish daily for illness. The sooner the treatment is initiated the better the chances are for recovery. When treating an illness remember to remove your carbon or activated charcoal from the tank.

Raising a brood of live-bearers can be a fun and educational experience. If you have any questions about these fish, you can always ask a pet store employee from where you have purchased your fish.