Garter Snake Care Guide

Garter snakes (genus Thamnophis) are among the most popular pet snakes for both novice and experienced reptile keepers. Their relatively small size, diurnal activity, and willingness to accept a variety of prey items make them rewarding captives. However, successful long-term care requires a thorough understanding of their specific environmental, nutritional, and medical needs. This guide synthesises current veterinary recommendations from the Association of Reptilian and Amphibian Veterinarians (ARAV), the Merck Veterinary Manual, and VCA Animal Hospitals to provide a comprehensive husbandry framework. Whether you are in North America, Europe, or Australia, the principles outlined here will help you maintain a healthy, thriving garter snake.

Quick Q&A

Question: What do garter snakes eat in captivity?
Answer: Garter snakes are strict carnivores that thrive on a varied diet of earthworms, small fish (e.g., guppies, silversides), and occasional amphibians. Wild-caught prey can carry parasites, so feeder fish should be captive-bred and thawed frozen to reduce pathogen and thiaminase risk. Always consult your veterinarian for a tailored feeding schedule.

Enclosure Requirements

Minimum Size and Dimensions

Garter snakes are active, diurnal reptiles that require horizontal space to explore. The Merck Veterinary Manual recommends that an adult single snake be housed in an enclosure at least 90 cm (36 in) long, 45 cm (18 in) wide, and 45 cm (18 in) tall, with a floor area of roughly 8100 cm² [1]. For each additional snake, increase the floor area by 50%. Larger enclosures (e.g., 120 cm x 60 cm) are preferable because they allow for a proper thermal gradient and enrichment.

A lid must be secure and ventilated; spring-loaded clips or locking screen covers prevent escapes. Garter snakes are agile climbers, so the lid should be tight-fitting, especially along the edges.

Substrate Options

Common substrates include:

• Aspen shavings (safe, low dust, absorbs moisture well).
• Cypress mulch (retains humidity better, useful for species requiring higher ambient moisture).
• Paper towels or reptile carpet (ideal for quarantine or sick individuals, as they allow easy monitoring of faeces and urates).

Avoid cedar or pine shavings; the aromatic oils are nephrotoxic and hepatotoxic in reptiles [2], per the VCA Animal Hospitals. Also avoid sand, which can cause gastrointestinal impaction if ingested.

Hides and Furnishings

Provide at least two hides: one on the warm end and one on the cool end. Hides should be low, snug, and opaque (e.g., half-logs, cork bark, resin caves). Additional enrichment includes:

• Branches for climbing (ensure stability).
• Artificial foliage (silk or plastic) to provide cover.
• A water dish large enough for the snake to fully submerge; soak to assist with shedding andhydration.

Humidity and Hydration

Ambient humidity should be 50–60% for most garter snakes, with a slight increase to 70–80% during the shedding cycle. This can be maintained by misting the enclosure daily or using a hygrometer-controlled humidifier. Change the water bowl at least every two days; snakes will often defecate in the water, so daily cleaning is advisable.

Diet and Feeding (Fish and Worms)

Garter snakes have a naturally varied diet that includes earthworms, small fish, amphibians, and occasionally small rodents. In captivity, providing nutritional variety is essential to avoid deficiencies.

Safe Food Items

1. Earthworms – Nightcrawlers (Lumbricus terrestris) or red wigglers (Eisenia fetida) are excellent staple prey. Red wigglers may produce a bitter secretion that some snakes reject; if so, use nightcrawlers. Always purchase from a reliable supplier to avoid chemical contaminants.

2. Fish – Small whole fish such as guppies, silversides, smelt, or chopped tilapia are good options. Important: Avoid fish high in thiaminase (e.g., goldfish, koi, shiners) because they destroy vitamin B1 (thiamine) and can lead to neurological disease. VCA Animal Hospitals state that “thiaminase-containing fish should be strictly avoided” [3]. Captive-bred feeder fish that are frozen for at least 30 days are safer than live fish, which may carry parasites (e.g., Spiroxys species [4]).

3. Amphibians – Occasional small frogs or tadpoles can be offered, but wild amphibians carry a high parasite load; use caution. In Australia, the Department of Agriculture, Fisheries and Forestry (DAFF) restricts certain amphibian imports to prevent chytrid fungus, so captive-bred anurans are preferable [5].

4. Pinky Mice – Small garter snakes (especially large adults) may take pinky mice as an occasional treat, but they are high in fat and low in calcium. The AVMA discourages routine rodent feeding for garter snakes because of potential nutritional imbalances and risk of obesity [6].

Feeding Frequency and Amount

• Hatchlings and juveniles (up to 1 year): Feed 1–2 appropriately sized prey items every 3–4 days.
• Adults: Feed 1–2 adult earthworms or several small fish once every 5–7 days.
• Prey size should be approximately the width of the snake’s widest part of the body.

Always feed prey that has been thawed completely and warmed to room temperature (not hot). Use feeding tongs to avoid accidental bites. Never leave live prey unattended with a snake; even earthworms can burrow if the snake is not hungry.

Supplementation

Multivitamin and calcium supplements (with vitamin D3) should be dusted on prey regularly: for growing juveniles, dust every feeding; for adults, once or twice per month. The European Food Safety Authority (EFSA) notes that balanced calcium:phosphorus ratios (2:1) are critical for proper bone and egg development [7].

Water Requirements

A large, clean water bowl should always be available. Many garter snakes drink while partially submerged, so the bowl must be heavy and stable to prevent tipping. Some species also benefit from a shallow “swimming area” for exercise. Change water at least every 48 hours.

Temperature and Thermal Gradient

Garter snakes are ectothermic and require a thermal gradient to thermoregulate. The AVMA and ARAV recommend a gradient from a basking spot to a cool zone [1,8].

Use a thermostat-controlled heat source (e.g., under-tank heater, ceramic heat emitter, or low-wattage basking bulb) placed on one side of the enclosure to create the gradient. Do not use hot rocks; they can cause severe thermal burns because garter snakes may not detect localized heat properly. The Cornell Feline Health Center advises that any heat source must be regulated by a dimmer or proportional thermostat [9].

A digital thermometer with probe placed at the cool end and another at the basking spot ensures accurate monitoring. Heat tape (flexible heat mat) is effective for bottom heat when placed under one third of the tank. However, glass enclosures should be raised slightly to allow airflow.

Seasonal Temperature Cycles

In the wild, garter snakes experience a natural brumation period (winter cooling). For captive breeding or those in cooler climates, a controlled cooling period of 8–12 weeks at 10–15 °C (50–60 °F) mimics their natural cycle and may improve reproductive success. This should only be undertaken with veterinary guidance and in healthy individuals (body condition score ≥ 3/5). Ensure the snake has access to water throughout.

Handling and Behaviour

Garter snakes are generally docile and tolerate handling well, but individual temperaments vary. The Canadian Veterinary Medical Association (CVMA) emphasises minimising stress during handling to reduce the risk of illness [10].

How to Handle Safely

• Support the snake’s body fully; never grip the head or tail alone.
• Allow the snake to move freely across your hands, avoiding sudden movements.
• Initial handling sessions should be short (5–10 minutes) and increase gradually.
• Avoid handling for at least 48 hours after feeding to prevent regurgitation.

Signs of Stress

• Musking (releasing a foul-smelling liquid from the cloaca).
• Tail vibration (a defensive display).
• Rapid, jerky tongue flicks and attempts to flee/hide.
• Refusal to eat.

If any aggressive behaviour is observed (e.g., biting, flattening the body), stop handling and allow the snake to retreat. Regular, gentle handling often reduces fear responses over time.

Quarantine for New Arrivals

The CVMA and ARAV recommend a minimum 90-day quarantine period for any new reptile introduced to an existing collection. During quarantine, use separate tools, feed separately, and monitor for clinical signs such as diarrhoea (or diarrhoea), weight loss, or respiratory sounds. Fecal examinations for nematodes and coccidia should be performed by a veterinary parasitologist [11].

Common Health Concerns

Garter snakes are resilient, but several diseases are well-known in herpetoculture.

Parasitic Infections

• Internal parasites – Roundworms, hookworms, and flagellates are common. Thamnophis spp. are particularly susceptible to Spiroxys worms (found in fish and amphibians). A fecal examination by a veterinarian is recommended twice yearly.
• External parasites – Mites (Ophionyssus natricis) can cause anaemia and skin infections. Treat with veterinary-approved acaricides (e.g., fipronil, permethrin-based sprays); always consult a reptile vet because some products are toxic to snakes.

Metabolic Bone Disease (MBD)

Caused by inadequate calcium or vitamin D3, poor UVB provision, or improper calcium:phosphorus ratio. Clinical signs include deformities of the spine (kyphosis, scoliosis), poor muscle tone, and tetany. Even though garter snakes are not highly dependent on UVB, UVB exposure (2–5% output) for 8–10 hours daily can support calcium metabolism. The Merck Veterinary Manual recommends providing UVB for reptiles with natural exposure needs [1], and several experienced keepers note improvements in overall health with UVB. However, the primary preventive measure is correct dietary supplementation.

Respiratory Infections

Present with open-mouth breathing, nasal discharge, or gurgling sounds. Often due to prolonged temperatures below 24 °C (75 °F) and high humidity. Treatment requires a veterinary visit for culture and antibiotic therapy; never use over-the-counter reptile medications, as they can be nephrotoxic.

Dysecdysis (Retained Shed)

Common when humidity is too low. If stuck shed does not resolve after a tepid bath and increased humidity, seek veterinary help to avoid constriction injuries, especially around the eyes (spectacles) and tail tip.

Nutritional Thiamine Deficiency

Occurs with excessive feeding of thiaminase-rich fish (e.g., goldfish). Signs: muscle fasciculations, retrocollis, and seizures. Immediate treatment with injectable thiamine (50–100 mg/kg) is life-saving. Prevention: avoid all fish from the carp/minnow family.

Parasite Zoonosis

While rare, some garter snake parasites (e.g., Spiroxys, Paratanaisia) are not zoonotic, but raw fish feeder fish may carry Anisakis helminths, which could be a risk to humans if contaminated hands contact food. The CFIA (Canadian Food Inspection Agency) recommends thorough hand washing after any reptile contact [12].

Regional Considerations

• Australia: Quarantine and licensing requirements for native garter snakes? (Note: garter snakes are not native to Australia; however, exotic reptiles are regulated by DAFF. Ensure any captive garter snake is legally obtained from a permitted importer/breeder.)
• Europe: The European Union bans the importation of wild-caught native amphibians and some fish species, which may affect feeder availability. Use captive-bred feeder fish (e.g., Poecilia reticulata).
• North America: Many states require permits for keeping Thamnophis sirtalis (Eastern garter snake) if taken from the wild; captive-bred are generally exempt.

Conclusion

Successful garter snake husbandry hinges on replicating their natural environment through proper enclosure dimensions, thermal gradients, a varied diet of earthworms and safe fish, and proactive health monitoring. Regular veterinary check-ups with a reptile specialist, combined with adherence to authoritative guidelines from the ARAV, Merck, and VCA, will ensure your garter snake lives a long, healthy life (up to 10–15 years in captivity). For any concerns about feeding, behaviour, or disease, consult a qualified veterinarian familiar with herpetological medicine.

References

[1] Merck Veterinary Manual. “Husbandry of Reptiles.” Merck Manuals, www.merckvetmanual.com/exotic-and-laboratory-animals/reptiles/husbandry-of-reptiles. Accessed 2025.

[2] VCA Animal Hospitals. “Substrates for Reptiles.” VCA Hospitals, https://vcahospitals.com/know-your-pet/substrates-for-reptiles.

[3] VCA Animal Hospitals. “Feeding Garter Snakes.” VCA Hospitals, https://vcahospitals.com/know-your-pet/feeding-garter-snakes.

[4] Denardo, D. (2000). “Parasites of Reptiles.” In Reptile Medicine and Surgery. Saunders.

[5] Department of Agriculture, Fisheries and Forestry (DAFF), Australia. “Import Conditions for Reptile Feed.” https://www.agriculture.gov.au/biosecurity-trade/import.

[6] AVMA. “Reptile Care Resources.” American Veterinary Medical Association, www.avma.org/resources/pet-owners/petcare/reptile-care.

[7] EFSA Panel on Nutrition. “Scientific Opinion on Dietary Reference Values for Calcium.” EFSA Journal, 2018.

[8] Association of Reptilian and Amphibian Veterinarians (ARAV). “Minimum Standards for Reptile Housing.” ARAV.org, www.arav.org.

[9] Cornell Feline Health Center. “Heating Protocols for Exotic Pets.” Cornell University College of Veterinary Medicine, 2021.

[10] Canadian Veterinary Medical Association (CVMA). “Recommendations for Handling Reptiles in Clinical Practice.” Can Vet J, 2023.

[11] Jacobson, E. R. (2007). Infectious Diseases and Pathology of Reptiles. CRC Press.

[12] Canadian Food Inspection Agency (CFIA). “Hand Hygiene for Pet Owners.” https://inspection.canada.ca/.