Whilst there are a few exceptions, two tarantulas cannot live together safely. Tarantulas are cannibalistic and are likely to eat each other, particularly in the confines of a small cage.
But what are exceptions? In what instances will two or more tarantulas live together?
Communal Tarantula Species
A small number of tarantula species are considered “communal” in that they will live together successfully.
Note that there is much disagreement in the tarantula hobby as to which species are truly communal. While some people have had luck keeping two or more tarantulas of the same species together, others have reported losses.
Generally speaking it is advisable to keep even “communal” tarantulas alone to prevent the risk of any specimen getting eaten.
Assuming you’re looking for a communal tarantula species though here are some of the most commonly-recommended species…
Socotra Island Blue Baboon (Monocentropus balfouri)
Monocentropus balfouri is considered by most tarantula enthusiasts to be the only “true” communal tarantula species. This species seems to play nicely with other specimens, even when kept in close confinement.
The Socotra Island Blue Baboon is a stunning species with it’s metallic blue legs. It is also a heavy webber which can create additional interest as a pet. These are not cheap to buy, however, thanks to their popularity.
If you want to start a colony of Monocentropus balfouri it is probably safest to start with a related group that have been together since birth. They can be slowly reared to maturity together. This is safer than buying individual specimens from various suppliers and then trying to introduce them to one another.
Indian Ornamentals (Poecilotheria spp.)
Some members of the Poecilotheria genus can live together, though note that this doesn’t apply to all species. Be sure to do your research in advance if you want to try a Poecilotheria communal setup.
There are also concerns that while spiderlings and juveniles may live together happily, as the specimens mature they seem to become more territorial and losses may be incurred.
Speaking from personal experience I have reared a group of Poecilotheria regalis to around a 3” legspan, before I split them up to make management and sexing easier. I have no idea if any losses would have been incurred should they have been left together. For the year or so they were together, however, I never experienced any aggression between specimens, and didn’t lose a single spider.
The key when keeping Poecilotheria together is not giving them too much space. It seems that a smaller cage seems to be more successful, whereupon the tarantulas do not set up a “territory” that they want to defend.
Trinidad Dwarf (Neoholothele incei)
N. incei is probably the “riskiest” option here. Some people report having successfully kept a group together, but others have ended up with just a single fat tarantula. While you may see N. incei being discussed as a communal species it is therefore probably not one to try in reality.
Cohabiting During Mating
Two tarantulas may live together for a period of time when you are attempting to breed them. This is often known in the hobby as “cohabiting”. Note, however, that this is only a temporary situation, and poses significant risks for the male tarantula.
Personally I have safely kept pairs of Chromatopelma cyaneopubescens, Omothymus violaceopes, Poecilotheria regalis, Poecilotheria ornata and Poecilotheria metallica together for weeks at a time without incident.
Be aware, however, that there is always a risk that you might wake up one morning to find your male has been eaten. This should only really be attempted therefore if you are actively trying to breed two mature tarantulas and you accept the likely outcome for your male.
Lastly, tarantulas will live together for a short period of time after hatching out of their eggs. However, the clock is ticking and it is only a matter of time until they start eating each other. Typically you’ll have just a few weeks before you start to see numbers dwindling.