Oryzias Minutillus

Datasheet

General Description

Oryzias Minutillus, commonly known as the Dwarf Medaka or Dwarf Ricefish, is a micropredatory fish with a maximum size of 1.7cm. Belonging to the Beloniformes order, this species is closely related to Oryzias pectoralis, Oryzias setnai, and Oryzias uwai. It boasts a rounded caudal fin and can be distinguished by its small size, rounded caudal fin, and specific fin ray counts.

Aquarium Setup

Best suited for heavily planted tanks with dark substrates, Oryzias Minutillus thrives in setups with patches of dense vegetation and some open spaces. They appreciate twisted roots, pieces of bogwood, and surface vegetation. Ideal water conditions include a hardness of 36-268ppm, pH levels of 6.0-7.5, and a temperature range of 23-32°C (see table).

Behaviour

Known for being generally peaceful, the Dwarf Medaka may not be an ideal addition to communities due to its small size. It shows non-aggressive behavior towards conspecifics and is most effective and confident when kept in groups of eight or more. When maintaining alongside other fish species, compatibility is best with diminutive species like Boraras, Trigonostigma, Danionella, and some Danio spp. It can also coexist with freshwater shrimp and smaller anabantoids.

Feeding and Diet

In nature, Oryzias Minutillus feeds on small insects, worms, crustaceans, and zooplankton. In an aquarium setting, they accept dried foods and benefit from daily meals of small live and frozen fare like Daphnia, Artemia, and bloodworms. Offering suitable flakes and granules is recommended to ensure a balanced diet.

Reproduction & Dimorphism

Breeding the Dwarf Medaka is relatively easy, with females capable of producing batches of eggs frequently. Spawning occurs in the morning, with males darkening in color and defending territories. The species displays sexual dimorphism, where males have extended dorsal and anal fin rays, a convex anal fin margin, and a short genital papilla, while females have a slightly concave anal fin margin, a bilobed genital papilla, and extended pelvic fin rays.

Habitat and Distribution

Oryzias Minutillus is found in fresh, standing waters like shallow pools, ditches, rice paddies, and clear water swamps. Their habitat is often abundant in aquatic vegetation, and they coexist with species like Dermogenys, Rasbora, and Channa. The species is distributed in Thailand, Cambodia, Myanmar, and parts of southern China, with regional variations noted by different researchers.