There are many ways to set up a dart frog tank. Some have waterways or drip wall systems or false bottoms, which are my favorites, as they help maintain the necessary humidty and help modify the temperatures. I've posted some pictures below of the most recent 20 gal. hex I just set up for a pumilio baby I need to separate from its parents relativey soon, because they are breeding again and will start picking on him. This is just one way of doing it, but its a really simple way.
You need to maintain a humidity above 80 degrees, and temperatures should generally range from 65 degrees at night (although some of the larger darts in particular can survive down to about 55 degrees F.) to 80 degrees during the day. A few can tolerate temperatures above this, but as a general rule, this range is what you should strive for. Also the rule of thumb is to allow 5 gallons of tank space per dart frog. You need to study up on the various species, however. Some such as tinctorius, azurius, and pumilios are best kept in mated pairs, since they are extremely territorial. Others such as D. leucomelas, D. imitator, D. galactonotus, D. castaneoticus, D. auaratus, P. terribilis, P vittatus, P. lugubris, get along in groups without much problem. D. reticulatus and D. fantasticus are thumbnails that really aren't good beginner frogs, and their sociability may vary.
I'd suggest that one of the first people to contact and read their care sheets are Patrick Nabors at Saurian and Black Jungle, although there are certainly other reliable breeders out there. I just haven't had personal experience with any but these two, at least not yet.
My very favorite of all the frogs I keep are the D. galatonotus, pumpkin orange "splash backs." This is due to their wonderfully bold personalities and ability to get along in larger groups.
Don't mix different color morphs of the same species, and don't mix species at all until you have some dart experience under your belt at least, and a very large tank.
I'll put the link to saurian at the bottom, which is saurian.net and all you need to do to contact Black Jungle is go to blackjungle.com
Link
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
6 D. galactonotus pumpkin orange splash back
7 D. imitator
6 D. leucomelas
5 D. pumilio Bastimentos
4 D. fantasticus
6 P. terribilis mint and organe
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus
2 P. lugubris