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Red Eye Crocodile Skink Care and Bioactive Maintenance

Red Eye Crocodile Skink Care and Bioactive Maintenance

Red-Eyed Crocodile Skink (Tribolonotus gracilis)

Difficulty: Intermediate

 Red-eyed crocodile skinks are small, terrestrial lizards native to New Guinea. They generally live among the plentiful leaf litter of the tropical forest floor, but have been found on coconut plantations as well. These skinks are nocturnal, which means that they are primarily active at night. As insectivores, they use this time to hunt nocturnal insects.

Red-eyed crocodile skinks are generally 7-9” long, with a lifespan of up to 10 years. They are sensitive to inappropriate husbandry and do not tolerate handling well, which means that these little lizards are relatively difficult to care for properly.

What You Need for a Bioactive Crocodile Skink Terrarium

Terrarium Size

The minimum enclosure size recommended for housing a single red-eyed crocodile skink is 24”L x 18”W x 18”H. However, when it comes to choosing a terrarium for pet reptiles, keep in mind that larger is always better!

As a general rule, crocodile skinks should not be housed together in the same enclosure, unless you plan to breed them. In that case, the enclosure minimum is going to be at least 36” x 18” x 18”.


Technically speaking, red-eyed crocodile skinks can survive without UVB lighting — instead relying on supplements for their vitamin D3 requirement. However, this is not best practice, as UVB provides benefits beyond just vitamin D3 synthesis, such as: preventing illness, improving nervous and digestive function, and improving mental health.

In other words, we recommend installing appropriate UVB lighting as part of your skink’s setup. The 12” Arcadia ShadeDweller UVB ProT5 Kit is likely to work the best for a red-eyed crocodile skink in a 18” tall bioactive enclosure. The skink should be able to get no closer than 8” below the UVB lamp.

Your UVB bulb must be replaced every 12 months to maintain its output. Resist the temptation to use other, cheaper brands — when it comes to UVB, brand matters!

Because this is a bioactive setup, you will also need a plant light to encourage healthy plant growth. We recommend the 12” Bio Dude Solar Grow T5 HO Single Bulb Light Strip for this purpose.

Both lighting and heating should be on for 12 hours/day.


Red-eyed crocodile skink temperature gradient:

  • Basking area temperature: 80-82°F
  • Cool zone temperature: 75-78°F
  • Nighttime temperature: 70-75°F

Ambient temperature should never rise higher than 82°F, or else your pet may get heat stroke! This species is very sensitive to heat.

To create a basking area for your red-eyed crocodile skink, you will need a low-wattage white heat bulb like the 50w Zoo Med Basking Spot Lamp and a fixture like the small Exo Terra Reptile Glow Light. Place the lamp on the extreme left or right of the setup. If the basking area gets too warm, you can plug the lamp into a lamp dimmer like the Lutron Credenza and reduce the heat that way. If the basking area is too cool, you will need a higher-wattage bulb.

Use a digital probe thermometer like the Bio Dude Digital Thermometer / Hygrometer to track your temperature gradient, with one temperature probe on the basking spot and one on the cool side.


Red-eyed crocodile skinks require a high humidity environment. To be specific, they need an average of 70-90% humidity. Keep track of your humidity levels with a digital hygrometer like the Bio Dude Digital Thermometer / Hygrometer, with the probe secured to a branch in the middle of the enclosure, preferably in a shaded area.

To raise humidity in your gecko’s enclosure and provide a source of drinking water, use an Exo Terra 2qt Mister to wet things down every morning and evening, preferably when it’s dark. If you need help increasing humidity, you can intermittently run a fogger/cool mist humidifier at night.


A thick layer of bioactive-compatible substrate is essential to creating a bioactive red-eyed crocodile skink enclosure.

First, layer ~2” of clay balls or Bio Dude HydroGrow drainage material and place a layer of tight mesh on top to help prevent soil from getting into the drainage layer.

Next you will need a soil-like mix that mimics the conditions of a tropical rainforest and will nourish your plants. If you want to make your own, you will need a mixture of 50% organic topsoil, 25% peat moss, and 25% play sand, around 24 quarts total. Mix that with leaf litter, sphagnum moss, and 4 doses of 6qt Bio Shot to inoculate your soil with beneficial microfauna. This layer of soil should be as deep as possible.

Alternatively, you can let The Bio Dude do the work for you with The Bio Dude’s Terra Fauna 24x18x18/24 bioactive substrate kit.

To make the substrate functional, make sure to add tropical CUC organisms like powder blue/orange isopods, dwarf isopods, and arid springtails. You can also add other species like dubia roaches, earthworms, and millipedes!

Decorating the Enclosure

Enclosure décor is more than just making your setup look good. It’s also an important part of providing environmental enrichment, which enhances your pet’s quality of life by providing opportunities to express natural behaviors. Given that crocodile skinks are a terrestrial species, you will need enrichment items like small cork hollows, caves, and foliage to give them ample opportunities to explore and hide. Don’t be afraid to clutter it up! Although it seems counterintuitive, the more opportunities your pet has to hide, the more comfortable it will be out in the open.

Live plants in particular are critical to helping your mini-ecosystem function properly. Moss is especially great for this species!

Feeding Your Red-Eyed Crocodile Skink

Crocodile skinks are insectivores, which means that they need to eat a varied diet of insects in order to get proper nutrition. Feed juveniles daily, and adults every other day. Offer enough insects for the skink to eat consecutively in a 5-minute period. Feeders should be no larger than the skink’s head.

The key to providing a healthy, balanced diet for any reptile is VARIETY! Here’s a quick list of foods that are safe to feed to your crocodile skink:

Best insects: crickets, dubia roaches, discoid roaches, snails, black soldier fly larvae, hornworms, silkworms, earthworms, mealworms, superworms


Although feeder insects should be gutloaded for 24-48 hours prior to feeding, they will also need to be “dusted” with an appropriate supplement powder just before. There are many options, but Arcadia CalciumPro Mg and MinerAll Outdoor are both solid D3-free calcium supplements. For best results, use as directed by the label.

Drinking Water

Crocodile skinks should have access to a water dish that is large enough for them to soak their entire body, but not deep enough to fully submerge. The water should be kept clean at all times, with the dish scrubbed out with veterinary-grade disinfectant weekly to discourage bacterial growth.


Care information courtesy of ReptiFiles.


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  • Josh Halter


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