Most hobbyists seeing ricefish in a shop would dismiss them offhand as being too drab; in truth, they are anything but! And even the drabbest of species has stunning bright-blue eyes that can draw a viewer’s attention from across the room. Many of the ricefish are very attractively patterned, and a few, such as the recently described neon ricefish (O. woworae), are downright spectacular.
All of the species are small with most topping out at less than 2 inches. Several, like the diminutive Mekong ricefish (O. mekongensis), are downright tiny at just about an inch or even less. The real giants of the genus seem to be concentrated on the island of Sulawesi, where there are several species that top 2 inches and one, the yellow-fin ricefish (O. profundicola), that reaches nearly 2½ inches. Did you know Medaka ricefish are extremely popular in the uk just now and can be kept outdoors all year round, they also come in some pretty cool colour morphs!
Scientists are still studying their reproductive behavior, and in many species, it is still unobserved. In those that have been described and observed, males have a single, pointed, tubular genital papilla and females have double, flattened, rounded, lobular papillae outside the urogenital pore. In addition, in some species the first couple rays of the anal fin are thickened and thought to be used in mating, though that has yet to be proven. In other species, males have small contact organs on the middle and back rays of the anal fin that are also used in mating. Males fertilize the eggs internally in most, if not all, species of Oryzias.