Hishio (Diamond-Tail) Medaka

Hishio (Diamond-Tail) Medaka key facts

Care level

Advanced

Lifespan

2-3 years

Size

Up to about 4cm SL

Temperature

18〜28℃

Diet

Prepared medaka food, green water

Lighting

Judging the trait depends on the shape of the tail and on whether the back carries light, so a container viewed from above suits it. The Medaka Web Encyclopedia recommends outdoor keeping and suggests shading half the container in summer.

Diet & Nutrition

Commercial prepared medaka food is the staple, given in an amount finished within a few minutes. Leftovers decay and foul the water, so adjust the quantity. Green water rich in phytoplankton suits fry rearing.

Water Temperature & Quality

Slightly acidic to slightly alkaline water is considered ideal, and the water drifts toward acidic as keeping continues. Around one water change per week is the guideline, and because sudden shifts in temperature or pH cause stress, acclimatise new fish by floating the bag. FishBase records the wild water chemistry of this species as pH 7.0-8.0 and hardness 9-19 dH.

Tank Mates & Compatibility

A peaceful schooling fish, normally kept as a group of the same variety. One litre of water per fish is the guideline against overcrowding; overstocking causes poor growth, reduced breeding, oxygen shortage and water fouling.

Breeding

Outdoors the spawning season runs from about April to October, once water reaches 18C or above with 12-13 hours of daylight. For year-round indoor breeding, 25-28C water and over 13 hours of lighting are the guideline. Eggs hatch at a cumulative 250 degree-days, about 10 days at 25C.

Health & Notes

Because even hishio pairings fix poorly, a reasonable number of fry is needed to select from. The trait is easily confused with a small-dorsal hikari fish, so judge it by light on the back, the gradation of body colour, and the difference in colour between head and flank.

About Hishio (Diamond-Tail) Medaka

Hishio medaka are improved medaka with a diamond-shaped tail fin on a normal or daruma body, a trait that doesn't breed true reliably. Best suited to experienced keepers; adults reach about 4cm.

7 things to know before welcoming a Hishio (Diamond-Tail) Medaka

1. 1Tail Shape Isn't Fixed

   Breeding two Hishio together doesn't guarantee diamond-shaped tails in the offspring. Standard tail shapes or other body types can still appear in the next generation, so maintaining the trait takes patient, repeated selective breeding.

2. 2Best For Experienced Keepers

   Hishio medaka are considered an advanced-level variety. Along with general medaka care basics, it helps to have an eye for judging tail shape and some experience with selective breeding.

3. 3Watch The Tail Shape

   Part of the appeal of Hishio is that each fish's diamond tail develops a little differently. Viewing them from above as they swim makes the tail outline easy to see and adds to the enjoyment of choosing individuals.

4. 4Keep Water Quality Stable

   As with medaka in general, sudden swings in temperature or water quality can affect their condition. Acclimate new fish slowly and keep up with regular water changes to maintain a stable environment.

5. 5Match Tankmates By Size

   To keep the tail fins looking their best, avoid housing Hishio with fish that might nip or damage them. If keeping them with other species, choose calm fish of a similar size and avoid overcrowding.

6. 6Set Up The Tank First

   Cycling the tank, filter, and any plants before bringing fish home reduces stress on your medaka. When introducing new fish, match the water temperature first, then acclimate them gradually.

7. 7Breeding Takes Patience

   Since Hishio is an improved variety, offspring won't necessarily inherit the same tail shape as their parents. Increasing fish with the desired trait means raising fry and continuing to select carefully over generations.

Frequently asked questions about Hishio (Diamond-Tail) Medaka

Q.Is Hishio medaka suitable for beginners?

A.Hishio medaka are generally considered an advanced-level variety. If you're new to keeping medaka, it's a good idea to build up some basic experience before taking these on.

Q.Will breeding two Hishio always produce Hishio offspring?

A.No, breeding two Hishio together doesn't guarantee that the diamond tail shape will be passed on reliably. The fixation rate is low, and offspring with a standard tail shape often appear.

Q.How big do Hishio medaka grow?

A.Adults reach a maximum standard length of about 4cm. There is some individual variation, but the size is comparable to other improved medaka varieties.

Q.Is Hishio different from Hikari body-type medaka?

A.The diamond-shaped tail is originally a trait of the Hikari body type, but Hishio refers to fish with a normal or daruma body that display this tail shape. Note that the body type itself is distinct from Hikari.

Q.How do you maintain the Hishio tail shape over generations?

A.The basic approach is to select fry that show a particularly clear diamond tail shape and use them for breeding. Continuing this selection patiently over multiple generations helps move the line closer to the desired tail shape.

Useful tools for Hishio (Diamond-Tail) Medaka care

Learn more about Hishio (Diamond-Tail) Medaka in the encyclopedia

More in this category