Oryzias Sp Red Cap Medaka Rice Fish
Species Profile
Red Cap Medaka Rice Fish (Oryzias latipes) feature a clean, pearlescent white-to-translucent body highlighted by a concentrated orange-red cap right over the crown of the head. While they look striking through the front glass, Japanese rice fish were selectively bred to be admired from above, making Red Caps especially impressive in shallow rimless tanks, mini ponds, and summer patio tubs. They are unfussy, deeply peaceful surface schoolers that bring steady movement to the top third of the scape, though their active surface-feeding habits mean a fitted lid is a smart precaution against accidental jumps.
**Note: All livestock orders will come carefully packaged with solid wall Styrofoam insulation and shipped via 1-day shipping only. No extra insulation needs to be added to your cart for your livestock.
Key Features & Notes
- Distinct orange-red crown marking over a pearlescent white body stands out in front and top-down views.
- Active surface-oriented swimmer that remains plant-safe and leaves foreground carpets undisturbed.
- Durable and cold-tolerant nature allows them to thrive in unheated indoor tanks, heated community setups, or outdoor tubs.
Acclimation & Care Instructions
- Float the sealed transport bag for 15 to 20 minutes to equalize water temperatures before opening.
- Drip acclimate over 30 to 45 minutes using airline tubing to ease them into your tank's GH, KH, and pH levels.
- Equip your tank with a snug lid or generous floating plant cover; Medakas can leap when startled.
- Provide gentle surface flow; strong currents from oversized filters can exhaust these top-level swimmers.
- Feed crushed flakes, micro pellets, or baby brine shrimp once or twice daily to match their small, upturned mouths.
- Keep in groups of 6 or more to encourage confident schooling behavior and reduce stress.
- Red cap size and body translucency vary naturally between individual fish and deepen as they mature under good light.
Quick Facts
Listed information should be treated as general guidelines only. Team Buce Plant encourages you to do thorough research to ensure healthy livestock!
| Attribute | Specification |
|---|---|
| Scientific Name | Oryzias latipes |
| Common Name(s) | Red Cap Medaka Rice Fish, Tancho Medaka, Japanese Rice Fish |
| Family | Adrianichthyidae |
| Care Difficulty | Easy |
| Diet | Omnivore (Crushed flakes, micro pellets, baby brine shrimp, daphnia) |
| Plant Safe | Yes (Safe with aquatic plants, carpets, and floaters) |
| Temperament | Peaceful upper-column schooler |
| Adult Size | 1.0"–1.5" (2.5–3.8 cm) |
| Minimum Tank Size | 10+ Gallons (Best in groups of 6+) |
| Water Parameters | pH 6.5–8.0 | GH 5–15 | KH 3–10 | 64°F–78°F (18°C–26°C; tolerates down to 40°F in tubs) |
| Freshwater Breeding | Yes (Prolific egg hangers on plants and spawning mops) |
| Origin | Japan (Tank-bred domestic strain) |
Frequently Asked Questions
1. How do I keep the red cap marking vibrant on my Medakas?
Full-spectrum lighting and diet play the biggest roles. Red pigments naturally intensify under bright lighting, which is why specimens kept in outdoor mini tubs or under dedicated high-output plant lights show deep cap saturation. Feeding a balanced diet that includes carotenoid-rich foods like live baby brine shrimp, daphnia, and quality spirulina-based micro foods will help maintain their cap color.
2. Do Red Cap Medaka Rice Fish require an aquarium heater?
Not in a standard indoor room. Japanese Medakas are eurythermal and handle wide temperature ranges with ease, thriving at typical room temperatures between 64°F and 74°F without a heater. They also work well in heated community aquariums up to 78°F or unheated outdoor mini ponds in spring and summer.
3. How do Medaka Rice Fish spawn, and how do I raise the fry?
Females produce small bunches of eggs that hang from their vent like tiny grape clusters before they brush them off into floating plant roots or artificial yarn mops. For a complete breakdown of setting up breeding tubs, collecting egg mops, and raising fry, read our Japanese Rice Fish Care Guide.
4. Are Red Cap Medakas safe to house with dwarf shrimp?
Yes. Adult Neocaridina and Caridina shrimp are safe companions. Medakas stay close to the waterline and have small upturned mouths, so they rarely cross paths with shrimp browsing the hardscape and substrate. Tiny shrimplets venturing into open surface water could be eaten, so maintaining thick moss patches or foreground ground cover provides plenty of protection for your colony.