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Hokkaido Salamander
Hynobius retardatus
The Hokkaido Salamander is a rare, primitive Asian amphibian native to Japan's freezing northern island. With a glossy dark brown body, it is remarkably adapted to survive extreme cold and frozen waters.
Class:Amphibia
Order:Caudata
Family:Hynobiidae
Genus:Hynobius
Species:Hynobius retardatus
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Environment
Terrestrial
Humidity
70 - 90 %
Day temperature
12 - 18 °C
Night temperature
8 - 12 °C
Ambient temperature
12 - 18 °C
Minimum enclosure
>= 45 L
UVB
Low
Species description
Geographical Origin and Habitat: A cryptic, ancient, and relict species endemic to the cold deciduous forests, snowmelt ponds, and marshes of Hokkaido Island, Japan. It inhabits damp leaf litter and glacial waters.
Taxonomy and Genetics: Belongs to the Hynobiidae family. Adults measure 12-18 cm in length, possessing a robust body and a cylindrical tail. The skin is remarkably smooth, glossy, and slimy. The dorsal coloration ranges from charcoal black to dark chocolate brown, sometimes speckled with tiny gold or grey flecks.
Behavior and Habits: Primarily terrestrial and fossorial. It spends a large portion of the year in deep hibernation or aestivation beneath rotting roots or underground to escape heat and drought. In spring, it migrates to water bodies to mate before the ice has fully melted. It feeds mainly on earthworms and other small invertebrates.
Morphology: Adult females are typically larger and stouter than males, particularly during the breeding season when carrying eggs. Males are identified by a visibly swollen cloaca during reproduction. The species reproduces by depositing twin sausage-shaped gelatinous egg sacs.
Care, breeding and tankmates
Terrarium Setup: Requires a horizontal terrarium (minimum 60x45x30 cm) with a deep, burrowing substrate (at least 15 cm of damp soil or coconut fiber topped with sphagnum moss) and a thick layer of leaf litter. Provide a large, shallow water dish or a separate aquatic area for the breeding phase.
Lighting and Heating: Adapted to extreme cold. Daytime temperatures must be kept between 12 and 18°C; temperatures exceeding 22°C can be fatal. Requires a significant night drop (8-12°C) and a winter hibernation period (2-6°C) in a cold room or refrigerator. Low-level (2-5%) UVB lighting is recommended.
Humidity and Hydration: Maintain high humidity levels between 80% and 100%. Spray the enclosure daily with declorinated or RO water. Proper ventilation is essential to prevent stagnant conditions and the growth of harmful bacteria or fungi.
Feeding and Supplementation: Strictly insectivorous and carnivorous. Feed on earthworms, small slugs, roaches, and bloodworms. Dust prey items with calcium and vitamin supplements 2-3 times a week to prevent metabolic bone disease.
Compatibility: A peaceful and gregarious species that can be housed in small groups. Because they are rare and protected, captive breeding should only be attempted by experienced keepers to maintain genetic purity.
Health and Common Diseases: Highly vulnerable to heat stress, which causes respiratory failure and rapid death. Poor hygiene of the substrate or water can lead to ammonia toxicity and skin infections. Avoid handling with bare hands as skin oils and body heat can harm them.
Geographic Origin and Distribution
A cryptic, ancient, and relict species endemic to the cold deciduous forests, snowmelt ponds, and marshes of Hokkaido Island, Japan. It inhabits damp leaf litter and glacial waters.
Origin
North AmericaEast Asia
Amphibian profile
- Diet
- No verified data available
- Life expectancy
- No verified data available
- Adult size
- 20 cm
- Lifestyle/Microhabitat
- No verified data available
- Activity cycle
- No verified data available
- Sociality
- No verified data available
- Reproduction
- No verified data available
- Toxicity
- No verified data available
- Life stage
- No verified data available
- Handling tolerance
- No verified data available
- Brumation
- No verified data available
- Molting
- No verified data available
The catalog's scalar value is 20 cm. The AmphiBIO v1 source reports a maximum adult measurement of 20 cm for this species, recorded as total length (TL). These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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