Medaka Fish
The many popular names attached to Oryzias latipes, such as "geisha girl," "medaka'," and "rice fish," give an indication of its former popularity as an aquarium pet. Originally coming from Japan, where it is called "medaka," the fish has many traits to hold the interest of fanciers.
Such a wealth of information is available on the medaka that it would be possible to present its entire embryology. The value of such a complete study to the ordinary aquarist is doubtful, however, and with a careful selection of the important material a concise elementary study would seem to be more profitable.
The female medaka possesses a single large ovary. This organ contains hundreds of eggs, all in different stages of development. As the eggs get more fully developed, they increase in size. This accounts for the swollen abdomen so characteristic of the female egg- layer. The female may produce from one to eighty eggs a day, depending on various conditions. These eggs are squeezed out of the female's body by a special set of muscles in the tube called the "oviduct." They arrive outside the body of the female, hanging like a bunch of grapes, and are there fertilized by the male. One male may be active enough to service many females, thus it is to your advantage to have an abundance of females with a minimum number of males.
The eggs hang outside the body of the female for four or five hours, unless they happen to be brushed off by a plant or on the bottom of the tank. The medaka will eat neither the eggs nor the young.
Care should be exercised in handling medakas as they are high jumpers. More peaceful aquarium fish are hard to find, and they further make themselves desirable by eating anything and everything, though they will make better parents if seasoned on live food.
