“Hello, my name is (removed) and I am interested in starting a poison dart frog tank. It’s my first time and I found your web site and was hoping you could help me a little bit. I’m interested in starting a tank with three types of frogs, a pair of D. tinctorius “French Guiana Cobalt”, a pair of D. Auratus “Costa Rican green and black”, and a pair of D. Leucomelas. I was wondering what size aquarium I would need for 6 frogs, and what all they would need to survive and thrive. Please email me back with some answers if you have any. Thanks a bunch.”
Use the largest one you have room for and can afford. I would not try it in an aquarium smaller than a standard 55 gallon, and more generally I would not recommend the mix.
There are a number of reasons not to keep these frogs together. First, these three species readily produce hybrids. There are examples of Dendrobatus auratus x D. tinctorius hybrids as well as D. auratus x D. leucomelas hybrids. Unlike other sectors of the herp hobby, breeding different species or even naturally occurring color morphs of the same species together is discouraged to help preserve the appearance that dart frogs naturally display from particular wild localities. To help preserve and manage existing captive dart frog populations, avoid housing different species together if there is a good chance of producing hybrids.
Alternatively, you could attempt to keep them together but then decide not to pull the eggs. Of course dart frogs are quite good at breeding without their keepers noticing and it isn’t uncommon for eggs to be laid, tadpoles to be transported to water, and then the tadpoles surviving through metamorphosis completely unknown to you, especially in large heavily planted terrariums. This is one of the fun things about keeping dart frogs as a hobby, but it also makes preventing producing hybrids difficult.
The second reason I would not recommend keeping these species together relates to the well being of the frogs. All three species (though especially Dendrobates tinctorius) are territorial, and not territorial as in they will sit at the top of a log and call to defend their spot (they’ll do this too) but territorial in that they physically fight. Although they can be kept under similar conditions and this is usually a good thing when keeping different species together, these three species also occupy similar niches and will be competing over resources such as food and breeding sites. Perhaps in an especially large enclosure this won’t be a problem, but in typical standard aquarium sizes it seems risky to me.
Your best option would be to keep all three species but separately. Set up three 20 gallon highs, one for each kind of frog. You’ll have just as much action going on and they will still make great display frogs, but you won’t run the risk of producing hybrids and you will eliminate the risk of one species out-competing the other for a resource like food.