Virtually all the medakas currently in the hobby are golden—this being considerably more colorful than the wild type. Japanese Medaka is popular not just because of its color but because of its breeding behavior. Of the other ten or so species in the genus, the following are most often seen: O. celebensis (Celebes Medaka) from Sulawesi; O. javanicus (Javanese Medaka) from Java; and O. melastigma (Spotted Medaka) from the area around Calcutta (India). O. nigrimas (Black Medaka) from Lake Poso in Sulawesi—in which some males are jet black—is rarely seen. All have similar requirements.
Other common names
- Golden Medaka, Japanese Ricefish, Geisha Girl
- Oryziidae (referred to as Oryziatidae by some authors)
- China, Japan, and South Korea; reported from Java and Malaysia.
- Around 1 1/2 in (4cm).
- Active shoaler.
- Wide range of foods accepted.
- Well illuminated, well planted, with open swimming areas, some clear surface area (i.e. free of floating vegetation), and water movement. Water chemistry not critical, but slightly alkaline, medium-hard water preferred. Temperature range: below 15°C (59°F) to above 28°C (82°F). These extremes should, however, be avoided in the long term.
- Eggs may be fertilized internally or externally; either way, the female carries them attached to the vent for a time before depositing them among fine-leaved vegetation. Hatching takes 7-10 days.