Jansen's black-tailed ratsnake — Care Sheet & Morphs

Husbandry requirements

Jansen's black-tailed ratsnake — origin: Endemic to the island of Sulawesi (Celebes) and neighbouring islands (Indonesia), in lowland and mid-mountain tropical rainforests..

Terrarium temperature gradient

Night min22 °C

Cool side24–26 °C

Warm side28–30 °C

A tropical forest species: avoid overheating. No intense hotspot is needed; a localised warm zone (an elevated branch) reaching 30-31 °C via a thermostat-controlled overhead heater is sufficient. Provide a horizontal and vertical thermal gradient. A night-time drop down to ~22 °C is beneficial.

Enclosure (adult)

120 × 60 × 150 cm

Vertical arboreal terrarium, planted / bioactive

A strictly arboreal species: prioritise height. These dimensions are a MINIMUM for an adult; a larger volume (150 x 80 x 180 cm or more) is strongly recommended. Provide sturdy horizontal and diagonal branches, dense foliage (real or artificial plants) to offer elevated hiding spots for this nervous species, and a very solid, locked lid (a powerful and restless snake).

Humidity

60–80 %

A humid tropical-forest atmosphere. Maintain 60-70% daily with peaks of 80-90% during sheds, through misting and a moisture-retaining substrate. Good ventilation is imperative to prevent stagnation and respiratory infections.

Substrate

Coconut fibre / soil free of fertiliser and pesticideDamp sphagnum mossLeaf litterFree-draining bioactive substrate with a drainage layer

A substrate that retains moisture without becoming waterlogged; a drainage layer and good aeration prevent waterlogging and the development of mould.

UVB

Recommended

A diurnal species: low-intensity UVB is recommended (Ferguson zone 1-2, ~5-6% tube / UVI 1-2) for well-being and metabolism, though not strictly essential if the diet is complete and varied. Provide shaded areas and avoid close direct exposure.

Water source

Always available

Provide a large bowl of clean water, stable and refreshed regularly (it also allows bathing and hydration). This arboreal species readily drinks the droplets deposited on branches and foliage after misting: mist daily.

Origin

Colubridae

Endemic to the island of Sulawesi (Celebes) and neighbouring islands (Indonesia), in lowland and mid-mountain tropical rainforests.

Feeding & health

Diet

Strict carnivore — In the wild: birds, bats and arboreal rodents (a visual hunter). In captivity: chicks, quail and appropriately sized rodents.

An active visual predator. Imported wild-caught specimens often prefer avian prey and may refuse rodents: scenting with a feather/chick helps the transition. Feed an adult every 7 to 14 days; monitor weight, as obesity is a risk in captivity. Thawed prey preferred.

Breeding

Oviparous

Clutch 5–12 eggs/young. Breeding triggered by a mild seasonal cycling (a drop in temperature/photoperiod and a variation in humidity). Incubation of about 60 to 80 days around 27-28 °C in a moist substrate. Captive breeding is still poorly documented for this species.

Health watch points

Respiratory infections (linked to unsuitable humidity/ventilation or temperature)
Internal and external parasites, common in imported wild-caught specimens (nematodes, protozoa, cryptosporidiosis): quarantine and a faecal exam are essential
Dehydration and difficult sheds (dysecdysis)
Chronic stress and food refusal, especially in wild-caught individuals
Thermal burns (unprotected heat sources) and stomatitis (mouth rot)

Morphs & genetics

Registry of 2 documented genes for Jansen's black-tailed ratsnake.

Leucistic (Wild Rumor) whiteRec
Melanistic / Hypermel dark phaseInc.d

Pairing calculator

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Jansen's black-tailed ratsnake × Jansen's black-tailed ratsnake

Probabilities per gene (independent loci).

Expected clutchSelect at least one gene on a parent.

Frequently asked questions

Answers to the most common questions about keeping the jansen's black-tailed ratsnake.

How big does Jansen's ratsnake get as an adult?▾

This species, endemic to Sulawesi, is noticeably larger than its cousin Gonyosoma oxycephalum: an adult typically measures between 180 and 230 cm, with a heavy, robust build. The contrast between the olive/brown body and the deep black tail becomes striking at this age.

What terrarium should be provided for an adult?▾

A strictly arboreal snake, it needs height above all: allow a minimum of 120 x 60 x 150 cm, though a volume of 150 x 80 x 180 cm or more is strongly recommended. Fit sturdy horizontal and diagonal branches along with dense foliage to give this nervous species elevated hiding spots, and secure the lid firmly - it is a powerful, restless animal.

What temperature should be maintained in the terrarium?▾

Native to the tropical forests of Sulawesi, it does not need an intense basking spot: a localised warm area up in the branches reaching 30-31°C via a thermostat-controlled overhead heater is sufficient, with a cool side between 24 and 26°C. A night-time drop to around 22°C is even beneficial.

Is UVB lighting required?▾

Although not strictly essential if the diet is complete and varied, low-intensity UVB (Ferguson zone 1-2, a tube around 5-6%, UVI 1-2) is recommended for the well-being of this diurnal species. Also provide shaded areas and avoid any close direct exposure.

What humidity level and substrate should be chosen?▾

This humid-forest species requires 60 to 80% humidity, kept around 60-70% day to day with peaks of 80-90% during sheds. Coconut fibre, fertiliser-free topsoil, damp sphagnum moss or dry leaf litter all work well, provided good ventilation is maintained to prevent stagnation and mould.

What does Jansen's ratsnake eat, and how often?▾

It is a visual hunter that feeds in the wild on birds, bats and arboreal rodents; in captivity, chicks, quail and appropriately sized rodents are offered. An adult is fed every 7 to 14 days - wild-caught specimens often prefer avian prey, and scenting with a feather or chick can help the transition to rodents.

How does this species stay hydrated?▾

Provide a large bowl of clean water refreshed regularly, which also allows for bathing. This arboreal snake particularly likes drinking droplets left on branches and foliage after a daily misting.

How long does it live, and what commitment does that represent?▾

Its lifespan is estimated at 15 to 20 years in captivity with appropriate care, although data remain limited for this species, which is still uncommon in the hobby. It is therefore a long-term commitment that should be anticipated before acquiring one.

Is this snake easy to handle?▾

No, the species' shy, nervous temperament makes it difficult to handle: when threatened, it laterally compresses its neck to rear up and appear larger, and may bite, though it is not venomous. Handling should be kept to a minimum, and this species is best left to experienced keepers.

Where does this species come from, and is it suitable for a beginner?▾

Jansen's ratsnake is endemic to the island of Sulawesi (Celebes) and neighbouring islands in Indonesia, where it lives in humid tropical forests. Rated as advanced difficulty, it is not a snake for beginners: its nervous temperament and precise humidity and ventilation requirements call for experience.

What are the most common health problems?▾

Respiratory infections linked to poorly regulated humidity or ventilation, internal and external parasites - common in imported wild-caught specimens - as well as dehydration and difficult sheds are the most frequent concerns. Quarantine and a faecal exam are essential when acquiring a wild-caught animal.

How does it breed in captivity?▾

Breeding is triggered by mild seasonal cycling of temperature and humidity. The eggs, between 5 and 12 per clutch, incubate for about 60 to 80 days at around 27-28°C in a moist substrate, though captive breeding remains poorly documented for this species.

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