A hardy, small, and colorful fish native to East Asia. Extremely popular in the outdoor pond hobby and nano aquariums. They are 'amphidromous' (tolerant of salinity changes) and can survive a wide range of temperatures, making them excellent tub/pond fish. They are surface dwellers that look best when viewed from above (top-down).
At a Glance
Tank Requirements
Water Parameters
Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard (Short Fin)
The typical form found in both ponds and aquariums. Includes famous color strains like Youkihi (Orange), Miyuki (Blue/Silver), and various sparkle (Lame) morphs. Extremely active and hardy.
Differs in 1 trait from base species
Also known as: Wild Type, Orange, Youkihi, Platinum, Miyuki, Galaxy, Lame, Tri-color
Long Finned
Selectively bred variants with extended dorsal and anal fins. These fish are not as agile as short-finned varieties and require strictly low flow to thrive. They should not be kept with fin-nippers.
Differs in 3 traits from base species
Also known as: Swallow, Wind, Real Long Fin, RLF
Japanese Ricefish (Medaka) Care Summary
The Japanese Ricefish (Medaka), scientifically known as Oryzias latipes, belongs to the Killifish family group. Adults reach a maximum size of approximately 4 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface zone of the aquarium and produces a low level of biological waste.
To thrive, the Japanese Ricefish (Medaka) requires a brackish tolerant aquarium with a minimum volume of 19 litres and a tank length of at least 30 cm. Water temperature should be maintained between 10°C and 28°C, with a pH range of 6.5–8.5 and a general hardness of 5–25 dGH. A low water flow is preferred. To replicate their natural habitat, the tank should include plants - densely covered and plants - floating.
As a schooling species, Japanese Ricefish (Medaka) should be kept in groups of at least 6. Keepers should be aware that this species is a known jumper, so a tight-fitting lid is essential. This species is available in 2 varieties: Standard (Short Fin) and Long Finned. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Similar Species
Dwarf Gourami
Trichogaster lalius
A peaceful to semi-aggressive labyrinth fish native to South Asia. Famous for their brilliant metallic blue and red stripes. While generally suitable for community tanks, males are territorial toward each other and similar-looking fish. They are sensitive to water quality and prone to Iridovirus if stressed. Requires access to the surface to breathe.
Red Rainbowfish
Glossolepis incisus
Native to Lake Sentani in Indonesia, this species is famous for the brilliant salmon-red coloration of mature males. They are large, active schooling fish that develop a distinct high-arched back as they age. Females are vastly different in appearance (olive-gold). They require hard, alkaline water and plenty of swimming space.
Cherry Shrimp
Neocaridina davidi
One of the most popular and hardy freshwater invertebrates in the hobby. They come in a rainbow of selectively bred colors. They are excellent scavengers and algae eaters, perfect for nano planted tanks. They are completely peaceful and have a negligible bioload, though they are highly vulnerable to predation by almost any fish with a mouth large enough to eat them.
Amano Shrimp
Caridina multidentata
A highly popular, industrious freshwater shrimp renowned for its unmatched algae-eating abilities. Popularized by aquascaper Takashi Amano, they are significantly larger and hardier than most dwarf shrimp (like Cherry Shrimp). They are notorious food-thieves during feeding time and excellent escape artists, requiring a tight-fitting lid. Their larvae require saltwater to develop, so they will not overpopulate in a freshwater aquarium.
Threadfin Rainbowfish
Iriatherina werneri
A delicate and exquisitely shaped nano rainbowfish native to New Guinea and Northern Australia. They are famous for the males' long, filamentous fins and butterfly-like display behavior. Due to their incredibly small throats, they require micro-foods. They are shoaling fish that are easily intimidated by boisterous tank mates.
Turquoise Rainbowfish
Melanotaenia lacustris
A stunning, deep-bodied rainbowfish endemic to Lake Kutubu in Papua New Guinea. Famous for their ability to shift colors from deep teal to bright iridescent blue depending on mood and water quality. They are active schooling fish that thrive in hard, alkaline water.