Livebearer Fish
For the beginning aquarist, the livebearers are the most interesting fish to breed. With no particular trouble they may be propagated easily and rapidly. As is implicit in their title, these fish bear their young alive, the eggs having been fertilized within the female by the male. It was once believed that livebearing fish are not truly viviparous (Latin for "livebearing"), but that they simply carry their eggs inside until they hatch.
Careful studies have revealed that some female livebearers contribute to the growth of their offspring in a way quite similar to that of higher, warm-blooded mothers, and that her young receive nourishment and other vital assistance from her during their period of prenatal life. Unlike mammalian mothers, however, the female live- bearer carries her developing young in the ovary, the same organ that produces the eggs from which they arise. There is no uterus in tropical fish. Another peculiar feature of practically all the livebearing fish found in aquaria is that they can have several broods after a single contact with a male. For example, female guppies have had as many as eight broods while being kept isolated from all males. This is made possible by the storage of the male sperm in the female's ovary.
One distinctive characteristic of most livebearersand a number of other fish, too—is their habit of eating their own young if the young are not separated from the parents as soon as they are dropped from the mother fish. The breeding trap is a helpful device to keep the mother away from her brood as she drops them. This is a small container constructed to fit inside the tank and into which the gravid female is placed. When the young are dropped from the mother fish, they fall right through the slotted bottom of the breeding trap and swim away into the rest of the tank. Some aquarists believe that these traps are rather dangerous to use, however, and that natural dense foliage (such as Nitella) better serves the same purpose.
There is no difficulty in getting viviparous fish to mate. All that seems necessary is to have one of each sex in the same tank and they will multiply. The sexes are easily distinguished in this type of fish: the female has a fully developed anal fin, while the male has a cylindrical, pointed gonopodium with which he fertilizes the female. Most of the viviparous young are matured and able to reproduce two to four months after birth.
It is best to choose the fish that you want to raise according to their physical characteristics: size, color, and vigor. Choose only those fish with the best color. If you are going to take the trouble to raise fish, you might just as well raise good fish with color and stature that you will admire and which will be admired by your friends. There is a feeling of satisfaction and success that comes from raising your own fish, so add to this pleasure by raising fish that you will be more than proud to display.
