The Mixed Species Dilemma

Posted by in Terrariums and Housing

Zoological institutions often recreate naturally occurring communities of reptiles and amphibians in large elaborate exhibits. Can a private hobbyist mix species and accomplish the same thing at home?

Yes and no. Usually hobbyists struggle to accommodate multiple species in one terrarium, and most should avoid attempting to do so, instead sticking to species-specific setups.

But can it work? Yes, though only in particular situations. First though, let’s go through some of the most common issues when different species are kept together in the same enclosure.

Enclosure Size

Enclosure size is the most common mistake made when keeping a community of reptiles and amphibians in a terrarium. It is important that all animals in the cage have room to have their own territory, hunt for food, regulate their body temperature, and otherwise behave normally without the threat of aggressive cage mates causing problems. Standard aquarium sizes are too small to accomplish this when multiple species are kept together, and the long, low rectangular shape most are manufactured in is rarely suitable for this purpose.

Next time you visit a zoo that has an exhibit featuring multiple species together make sure to take note of the size of the enclosure. Most are large cubes that that measure several feet or more in length, width, and height, and a similar cage size should be applied if reptiles and amphibians are kept together at home.

Terrarium at CalAcademy with frogs and geckos together

A large terrarium at the California Academy of Sciences housing a Costa Rican community of dart frogs, small geckos, and glass frogs. Note the size of the enclosure, which reaches several feet in all directions.

It is also important to understand that a terrarium offers less room than nature. In the wild there is plenty of space for reptiles and amphibians to go about their business. It’s rare for two different species to come near each other unless one is trying to eat the other. When multiple species are placed into a small glass box there is a greater chance that something will go wrong than there is even when species coexist in nature.


Although they may be your pets, reptiles and amphibians are also usually happy to eat each other if the opportunity arises. The size of prey that can fit inside an amphibian’s or reptile’s mouth is often surprising. As a general rule, only keep different species together that are the same size or will not attempt to eat one another. Consider also that when kept in close quarters with one another, the leg of one species make look like food to another if particularly voracious or aggressive species are housed with others.

A poison dart frog (Phyllobates terribilis) attempting to eat a mourning gecko (Lepidodactylus lugubris) it was housed with. They were housed together for ~1 year before the predation attempt. The frog survived after the gecko was removed from its mouth. Photo by Devin Davidson.

Conflicting Environments

Accommodating different environmental needs for multiple species in one enclosure is difficult and sometimes impossible to do. If the environments needed by different species don’t match up they should not be kept together.

Particularly important is temperature. Reptiles must be provided with a range of temperatures that may differ as much as 25°F or more from one side to the other, while most amphibians do not need such a large thermogradient. It is difficult to accommodate different temperature requirements in one enclosure and this can make mixing reptiles with amphibians challenging. The preferred humidity level and moisture in the environment is also important to take into consideration. Species from arid regions should never be kept with those from tropical climates.

In addition to temperature and humidity, the physical features of the environment are important too. Some species are aquatic and will need a large water area, while others are strictly terrestrial and can drown in deep water. Some species prefer a deep soil substrate that they can burrow in, while others are arboreal and need different perches and climbing spots.

Terrarium at HVZ

This terrarium houses several species of Neotropical frogs together. It is planted to allow different microclimates within and the upper reaches are brighter and hotter than below.


An often overlooked issue is the toxicity of the animals being kept. Keeping poisonous species of amphibians with other animals is risky for obvious reasons. Some commonly encountered species of amphibians that are poisonous are fire-bellied toads (Bombina species), red-banded walking frogs (Phrynomantis bifasciatus), fire-legged running frogs (Kassina species), most toads (family Bufonidae), Cuban tree frogs (Osteopilus septentrionalis), tomato frogs (Dyscophus species), and most newts and salamanders. These amphibians should not be housed with others, especially when the other species may be prone to attacking or feeding on them.

Dietary Differences

Some amphibians and reptiles that are close to the same size, live in similar environments, are not poisonous in captivity, and would presumably do fine if kept together sometimes do poorly because they require different types of food to eat. Diet is one of the most important aspects of reptile and amphibian captive husbandry. Unfortunately, not all species eat the same foods, and those that do often do not eat the same sizes of food, and this needs to be taken into consideration.

For example, both red-eyed tree frogs (Agalychnis callidryas) and green and black poison dart frogs (Dendrobates auratus) inhabit similar environments, are not especially aggressive, are not poisonous in captivity and would otherwise seem like they might coexist well. However, a large difference in their captive care requirements is diet. The tree frog will only recognize larger invertebrates as food, while dart frogs have difficulty eating anything other than the tiniest of prey. Although feeding both sizes of food is one possible solution, this could end poorly because large feeder insects such as crickets that go unnoticed may attempt to eat reptiles and amphibians that do not eat them first. In the above mentioned scenario, the adult crickets for the red-eyed tree frog could potentially harm the dart frogs.

It is also important to understand that not all reptiles and amphibians are equipped equally to catch prey. Those that are stronger often bully other weaker species out of food and will out-compete the weaker species when kept together.


Finally, it is important to point out that keeping different species together—especially those from different sources, or field collected reptiles and amphibians from different areas—increases the risk of foreign pathogens being transmitted. Before keeping different species together it is necessary to keep them both separately for some time to ensure they are in good health. Two or three months isolated from one another is usually long enough to identify a health problem, however, even in a case where both species appear healthy it is still possible that one may be carrying a disease the other is particularly susceptible to. Health screening by a veterinarian can help reduce this risk.

So, the big question: What species of reptiles and amphibians can coexist together in captivity?

This may sound condescending, but I am going to go ahead and put it here anyways. If you have to ask whether or not two different species can be kept together you should not attempt mixing them because you don’t understand their care requirements enough to do so and do not have the experience needed to identify common problems that may develop in a terrarium housing multiple species.

Some examples of multi-species setups that have worked well are provided below. Note these are not recommendations.

  • Some North American tree frogs can coexist well together, such as green tree frogs (Hyla cinerea) and gray tree frogs (Hyla versicolor). These species require fairly similar care and can be kept together in a roomy enclosure. Avoid keeping Cuban tree frogs (Osteopilus septentrionalis) with other frogs because they are poisonous, grow large, and love to eat other amphibians.
  • Certain species of poison dart frogs (Dendrobatidae) have been kept together successfully. Stick to dart frogs from different genera, such as Dendrobates tinctorius with Phyllobates bicolor, and only do so in an especially large terrarium, separating species or individuals if aggression is noticed.
  • Anoles (Anolis species) are a common lizard that is often seen kept with frogs, but I would advise against this unless the terrarium is large and a significant temperature gradient can be provided safely without risking the frog’s safety. It also can be difficult to locate healthy anoles since most are wild-caught and unhealthy animals should never be kept with others.
  • Small day geckos (Phelsuma species) and the tiny parthenogenic mourning gecko (Lepidodactylus lugubris) have also successfully been kept with certain species of frogs, but again the same precautions should be taken as when keeping anoles with amphibians. Ensure geckos and frogs are healthy before introducing them and only do so in an especially roomy terrarium.
  • Aquatic basking turtles, such as painted turtles (Chrysemys picta), red-eared sliders (Trachemys scripta), and map turtles (Graptemys species) may live well together, although it’s important to watch for behavioral problems and to pay attention to differences in dietary requirements.

As general rule, avoid mixing snakes with other reptiles and amphibians because their care requirements are often different than those of other types of herps. Avoid mixing turtles and tortoises with other types of reptiles and amphibians for the same reason. The exception may be in large greenhouses or terrariums of a similar size where it may be possible to accommodate turtles or tortoises with another species. Larger reptiles, such as monitors or boids, are almost always best kept either alone or with others of the same species because they are too difficult to manage when kept in terrariums with other reptiles and amphibians.

None of the above combinations are foolproof or without risk. Whenever two species are kept together there is usually a greater chance that problems will occur than when they are kept separate, and it is important to understand this before mixing species.

Before keeping different species together

Quarantine. Prior to keeping different species together it iscrucial that all animals are isolated in separate enclosures to ensure they are healthy. During this period of time, observe all animals careful. In isolate, the enclosures should be kept as clean as possible, and it is advised that the keeper washes their hands and any shared equipment between cages to prevent possible pathogens from spreading between them. Even better, use dedicated equipment and gloves. I also always recommend a veterinarian examine new acquisitions when possible, and this is especially important if the animals are intended to coexist with another species in the same enclosure.

CB vs. WC. As always, go for captive-bred stock from a trusted breeder rather than mixing wild-caught individuals. Amphibians and reptiles born in captivity are less likely to have health problems than those that were recently collected from the field, and may be less likely to harbor harmful diseases. There are also ethical and moral dilemmas involved in using wild-caught reptiles or amphibians for display together. By only mixing captive-bred animals, the risks involved in keeping a community reptile or amphibian terrarium will be reduced.


What not to do. This combination is bound for failure.


To conclude, keeping different species together successfully takes experience, research, time, money, and space to provide and the community tank is something that most hobbyists and private breeders are unable to do safely and with long-term success. Although it is common to see mixed community tanks at zoological institutions, these facilities are better able to provide the care needed to maintain them. They have fulltime veterinarians on staff so that when problems do occur a vet can be called in immediately. Zoos also have other resources that the average hobbyist does not, such as a team of keepers who specialize in maintaining animals. The community amphibian and reptile tank is something that may be fine to attempt for veteran hobbyists who have the resources and experience needed to maintain one, but for those who are relatively new to keeping reptiles and amphibians or maintain large exhibits I would always recommend housing different species separately.