Thread: PLEASE READ-Mixing species

Mixing species of reptiles and amphibians is always a controversial subject. Some people may have luck with it, but for the majority of keepers, it is not something that is advised and it has the potential to go very horribly wrong. Very often, people post threads asking about whether they can mix ?this? with ?that?, and so here I hope to clarify some of the reasons mixing species does not normally work. Many pet shops will mix species together to save space, and even recommend to customers that they are fine together, even when they most likely will not be for the long term. This post is not intended to be an attack on anyone who does mix species, and nor is it supposed to lay down ?the rules? that you must follow. It is simply information about the very important considerations that must be made when thinking about mixing species, and an attempt to help people wondering why people say it shouldn?t be done.
I have tried to base the majority of this information on science, and not just the hear-say and gossip that inevitably gets passed around as fact. Some people will have success with mixing species, and there are very rare exceptions to the general rules where 2 species are relatively compatible, but before you attempt mixing species, you must 1st be armed with as much knowledge about the problems as possible.

• Conditions.

As herptiles are ectotherms (cannot regulate their internal body conditions) living conditions are even more important than in other taxa. The species available in the pet trade come from a wide range of countries and environments which need to be simulated in their captive housing. This is the 1st consideration you must make when thinking of mixing species. How will you provide both species with its optimum conditions in the same vivarium? Even species that originate from the same country will need different conditions as in the wild they inhabit niches that are individual to them and provide them with the perfect conditions. For example, The Whites Tree frog (Litorea caerulea) is found in Australia, as is the Bearded Dragon (Pogona vitticeps). However, these 2 species need completely different conditions, and a Whites tree frog could certainly not survive in a set up designed for Bearded dragon. Even species that come from the same type of habitat, such as the whites tree frog and Red-eyed tree frog will require slightly different conditions to thrive, even though they both come from humid rainforest type environments. Without having a zoo-sized exhibit (beyond the means of most private keepers) it is impossible to provide both species with optimum conditions, and so 1 or both species will have to be compromised. This may not affect them in the short term, but as with all these issues, it may impact the long-term health of the animals.

• Fighting and stress.

Many species are highly territorial, and as most would not encounter one another in a wild situation, there is always the risk of fighting between vivarium occupants. This is an issue with same species groups, let alone mixed species. When there is a size difference between the species, the smaller species may often be looked upon as a prey item, and the larger will attempt to eat the smaller.

Reptiles and amphibians are very susceptible to illness from stress. Lactic acid builds up in the system as the stressed animal respires anaerobically, and can often reach fatal levels. When mixing species, the animals are kept in much closer proximity than they would ever normally be in the wild and moreover, they cannot escape. Over time this will cause great stress to the animals. Most people will agree that they want to keep their animals as healthy and naturally as possible, and in the wild they would not be forced to spend time close to another species in the way a vivarium does.

• Competition

Different species have different habits and methods of catching prey and feeding, and these often conflict causing competition issues in a mixed vivarium. I will use species I know well to demonstrate my point here. The Whites tree frog will wait very patiently, still and silent until the exact moment to strike, and then it jumps onto its prey. This can be a few minutes even! The Crested gecko on the other hand is much more rash in its hunting methods, and will pounce on a prey item with seemingly little forethought. If these 2 species were kept in the same enclosure, the geckos hunting method would likely cause the patient frog to be out-competed as it?s silent and still approach would be disrupted. Even issues other than food may be competed over, for example, who gets the best basking site? Who gets to use the ?best? hide?

• The Chemistry.

All animal species in the world carry unique bacteria and protozoans that aid different processes to us, and in return they cause us no harm and we allow them to use the body of its host as protection and habitat. This process is called symbiosis. When 2 species come into close contact (as would happen in a vivarium) the symbionts from 1 species will get passed onto the other, and this may cause the 2nd species to become ill. What is harmless and healthy for 1 species is not for another. With WC animals, these problems are exacerbated, as you not only have to deal with symbionts, but parasites and illnesses that the other species will not be resistant to as they would not have been naturally exposed to them.
With amphibians, the problems of chemistry are all the more severe, as they are particularly sensitive to external environment due to their semi-permeable skin. Even their own ammonia can kill them if water is not changed frequently enough, so add to that the waste products of another species and you have even worse problems. All amphibians produce toxic secretions from their skin, and while they may be so weak that they do not pose a health issue to us, another species, which is going to come into contact with the toxins in their environment, in their water supply, and potentially on their food, this may cause a serious health issue. Fire-bellied toads are one of the most toxic commonly kept amphibians, and I often get asked if they can be mixed with other species!

• Habits.

When considering mixing species, thought must be given to how the different habits of the species will conflict. Diurnal species such as Anoles may conflict with nocturnal species (i.e. most geckos) as whilst one is sleeping, the other is active and may disturb the other. This is likely to cause stress.


As I said at the beginning of this post, some people do have ?success? with mixing species. However, a lot of these issues will not become apparent in the short term. It may be months, even years before the extent of the problems takes effect and as reptiles have such different mechanisms for displaying illhealth than mammals, we may not spot the signs until it is too late. Before you even contemplate mixing species, you need to have kept each species separately, for long enough that you can know the ins and outs of each individuals eating habits, behaviours, appearance? so that if something is wrong, you can spot it. Mixing species should NOT be done for the conservation of space. This is not a good reason to mix, as the size of enclosure that a mixed exhibit will need is far bigger than the vivariums each species would need separately. Certain exceptions apply, as in all fields, but this should not be taken lightly either as it is not always successful. Whites tree frogs may be kept successfully with Whites lipped tree frogs (same genus, Litorea) and likewise, Crested geckos have been kept with Mossy geckos (same genus again, Rhacodactylus). However, these are exceptions. Crested geckos may not be kept with any other member of their family such as the Gargoyle gecko or Leachianus, and so it is not simply a matter of how related 2 species are.

I hope that this will be interesting and useful to people considering mixing species.