Selective Breeding

Where art meets science

Growing the hobby

Supporting hobbyists with products and knowledge

Customer Service

Everyone's expereince is important

Medaka Fish Care & Breeding Hub

5+1 Ulysses Japanese Rice (Medaka) Fish. High Quality US bred Juvies

Welcome to the ultimate Medaka (Japanese Ricefish) resource by BARCK Aquatics. This pillar page is designed to be the central knowledge hub for medaka care, breeding, genetics, and buying healthy, high‑quality fish in the United States. Links to blogs will be added as I build this knowledge hub. Whether you're brand new to medaka or an experienced breeder refining bloodlines, you'll find practical, experience‑based guidance here.

What Are Medaka Ricefish?

Medaka (Oryzias latipes), also known as Japanese Ricefish, are small, cold‑tolerant freshwater fish prized for their vibrant colors, hardiness, and ease of breeding. Unlike tropical fish, medaka thrive in a wide temperature range and are well suited for both indoor aquariums and outdoor tubs.

Why medaka are so popular:

Hardy and beginner‑friendly
Fascinating genetics and strain diversity
Suitable for unheated tanks
Can be kept indoors or out
Active breeders with visible egg development

📝 Exploring the World of Medaka Rice Fish: Care and Breeding Guide

Medaka Care Basics

Tank Size & Setup

Medaka can thrive in small aquariums, planters, or really any container larger than 1 gallon, but stability improves with volume. A 10–20 gallon container or larger is ideal for long‑term success, but containers as small as 1 gallon can be used if only keeping a few fish.

📝 The Ultimate Guide to Making Your Own Medaka Mini Pond

Key setup tips:

Filterless set ups are OK
Gentle flow
Live plants or moss for cover
Open swimming space
Medaka love sunshine

📝 Deep dive: Hamburg Matten Filter for Shrimp & Medaka

Water Parameters

Medaka are forgiving, but consistency matters.

Temperature: 40–85°F (ideal 65–80°F). Medaka can survive short-term in an even wider range, from just above freezing up to 100°F.
pH: 6.5–8.0

📝 Learn more: Medaka Temperature Tolerance & Torpor Explained

Feeding Medaka

A varied diet brings out the best color and breeding behavior.

High‑quality pellets
Live foods (daphnia, baby brine shrimp)
Frozen foods

📝 Related post: Photosynthetic Bacteria as food for fry

Medaka Breeding & Egg Care

Medaka are prolific breeders and lay eggs almost daily under proper conditions.

Breeding Behavior

Eggs carried by females before being deposited
Best ratios: 1 male to 2–3 females
Increased activity during summer months (longer photoperiod)

Egg Collection & Incubation

Eggs hatch in 7–14 days depending on temperature — use our Medaka Egg Hatch Calculator
Can be hatched in small containers or breeder boxes
Light exposure influences development

📝 Step‑by‑step: How to Hatch Medaka Eggs Successfully

Medaka Genetics & Strains

🧬 Genetics-Driven Stock: BARCK Aquatics medaka are selectively bred for stable traits and long-term line health.

One of the most exciting aspects of medaka is genetics. Selective breeding has produced hundreds of strains with unique traits.

Common Genetic Terms Explained

Lamé: Reflective scale type
Light Type: Internal vs. external light expression
Hikari: Shimmering body lines

📝 Genetics series:

Coming soon

Seasonal Behavior & Torpor

Image shows medaka mini pond that is iced over.

Unlike tropical fish, medaka can enter a torpor‑like state in colder temperatures.

What Is Medaka Torpor?

Reduced metabolism
Slower movement
Energy conservation

This natural process supports long‑term health and breeding vigor.

📝 Educational guide: Overwintering your beloved Medaka

Buying Medaka Fish Online

🛒 Shop Medaka: USA-bred medaka strains, mosses, and aquatics shipped with proven methods.

Not all medaka are created equal. Genetics and maintenance of line characteristics, shipping practices, and breeder experience matter.

What to Look For in a Medaka Breeder

USA‑based stock
Stable genetics (not mass imports)
Proven shipping methods
Clear strain identification
Trusted, reputable breeder

Why choose BARCK Aquatics:

100% USA-Bred Stock: We never mass-import. All our medaka are raised locally, meaning they are fully acclimated and experience far less shipping stress.
Bred On-Site by Jim: Every fish sold is selectively bred and raised right here at our facility, ensuring strict quality control and healthy genetics.
Premium, Stable Genetics: We manage a rigorous breeding program to maintain vibrant colors, strong lines, and stable traits across all our strains.
Safe & Humane Shipping: We use proven packaging methods to ensure live, healthy arrivals, backed by a clear and fair DOA policy.
Dedicated Hobbyist Support: We do more than just sell fish—we are here to help you succeed with expert advice, detailed care guides, and responsive customer service.

📝 Helpful reads:

Is BARCK Aquatics Safe to Buy From? See customer reviews here

Medaka FAQs

Are medaka good for beginners?
Yes. They are among the easiest fish to keep and breed.

Do medaka need heaters?
No. They thrive in unheated tanks in most homes.

Can medaka live with shrimp?
Yes, especially with Neocaridina and dense plant cover.

Explore BARCK Aquatics Medaka Resources

This page is the foundation of our medaka content. Each linked article goes deeper into a specific topic, helping you master medaka care and breeding while supporting ethical, genetics‑driven aquaculture.

Blogs in the works: