Deep Sea Medaka
Discover the refined beauty of the Deep Sea medaka (Japanese name: 深海メダカ). Known in Japan as Shinkai, this strain is admired for its soft, elegant blue tone that resembles the clarity of deep ocean light rather than darkness.
The Deep Sea medaka was developed in 2010 by Japanese creator Ryusei Nagaoka (長岡龍聖). It originated from Blue Miyuki (青幹之) lines that showed a rare internal blue peritoneum. Through years of selective breeding, external shine and black pigmentation were gradually removed to highlight this internal feature, known as fukumaku ao.
While its name evokes depth and mystery, this medaka’s refined appearance offers a tranquil yet captivating presence. It stands out beautifully in black tubs or among white-bodied medaka.
Strain Name (品種名): Shinkai (Deep Sea)
Creator (作出者): Ryusei Nagaoka (長岡龍聖)
Released: 2010
Key Trait: Blue peritoneum (fukumaku ao)
Lineage: Derived from Blue Miyuki, selectively refined for internal blue clarity
Learn more about the Deep Sea medaka on our Medaka Encyclopedia page.
Understanding Live Fish Options
Here’s a quick guide to help you choose the right option when purchasing live medaka from our shop. Sizes and sexing are carefully selected, but please note that fish may vary slightly by strain, age, and growth rate.
Juvenile (Unsexed)
Young fish, typically 1.0–2.5 cm in size. They are too early to sex and often have not fully developed their final traits yet. As such, they are not graded for color, pattern, or fin type at this stage.
Female
Confirmed female medaka, usually 2.5–3.5 cm. Selected by experienced staff, but please note that 100% accuracy cannot be guaranteed for younger fish.
Male
Confirmed male medaka, also typically 2.5–3.5 cm. Identified by fin shape and behavior, but final confirmation may develop with maturity.
Breeding Pair (1 Male + 1 Female)
One male and one female—ideal for those starting a breeding line or looking for a guaranteed pair.
Trio (2 Females + 1 Male)
One male and two females. This setup helps maximize egg production and is commonly used by breeders.
SS Grade Pair
A premium hand-selected male and female pair with top-level traits. These are our highest-grade specimens, chosen for exceptional color, form, and balance — ideal for serious breeders and collectors.
⚠️ Please note: Sexing is done to the best of our ability at the time of shipping. Juveniles cannot be sexed or graded for traits. Some strains—especially short-body types like Daruma—naturally grow smaller than standard-bodied medaka. In some cases, longfin or swallow-tail varieties may be difficult to sex accurately due to their flowing fins and slower development. If you believe there is an error in the sex of the fish you received, please don’t hesitate to reach out via our Contact Us page.
🐟 If your goal is serious breeding, we highly recommend purchasing multiple breeding pairs or at least two trios. Just like people, medaka have their own personalities and chemistry — and not all combinations will result in successful breeding. Having more than one group increases your chances of forming compatible pairs and achieving strong egg production.
Get more, save more! 🎉
| Buy quantity | Discount |
|---|---|
| Buy 2 - 3 | Get 5% off |
| Buy 4 - 5 | Get 10% off |
| Buy 6+ | Get 15% off |
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Important Information
Important Information
Imported in Fall 2024 and Spring 2025. All options currently available are U.S.-bred.
Our fish are raised outdoors in North Carolina, under natural sunlight.
As of September 2025, outdoor temperatures range from the 60s to mid-70s (°F), with a stable pH around 7.
Shipping Information
Shipping Information
Live Fish Shipping Rates (Flat Rate – Continental U.S. Only)
To make things easier and ensure your medaka arrive safe and sound, we've introduced a flat rate shipping system so you can shop without worrying about complicated or unexpected shipping costs.
| Box Size | Max Fish | Max Pairs | UPS 3 Day Select | UPS 2nd Day Air | UPS Next Day Air |
|---|---|---|---|---|---|
| Small | Up to 10 fish | Up to 5 pairs | $19.99 | $22.99 | $57.99 |
| Medium | Up to 20 fish | Up to 10 pairs | $25.99 | $34.99 | $59.99 |
| Large | Up to 30 fish | Up to 15 pairs | $34.99 | $47.99 | $83.99 |
Additional Notes:
- Hawaii & Alaska: Excluded from flat rate shipping.
- $3 packing fee per order – includes insulation, styrofoam box, and materials
- Dry goods ship free when purchased alone. If combined with live fish, only the live fish shipping rate applies.
- No USPS – we use UPS only for all live fish orders.
- Free shipping on orders over $500
- All live fish orders are covered by our DOA guarantee, regardless of shipping speed
- Local pickup is free but must be pre-arranged before purchase
Shipping Schedule:
- We ship only on Mondays and Tuesdays to minimize weekend delays.
- Orders placed after Tuesday 12 PM EST will be shipped the following Monday.
Delayed Shipment Claim:
If your package arrives later than your selected UPS service, you may file a claim with UPS. Please take photos of the shipping label and the box and email them to snrmedaka@gmail.com.
Dry Goods Free Shipping:
Dry goods are shipped via USPS Ground or First Class, depending on the total weight. If you need faster delivery, you may request expedited shipping for an additional fee. Please contact us via email to arrange upgraded shipping: snrmedaka@gmail.com
Healthy and beautiful fish! Will be purchasing more strains in the future! Very reliable seller!
Received 4 of the most beautiful and cutest babies. Carefully packed, shipped and arrived on time and healthy. Will continue to monitor available medaka to add to the family!
