I agree totally, especially with the suggestion that one should have some experience with indiviual dart species before considering mixing with anything else, even different species of darts. They are entertaining and challenging enough in themselves, and 40 gallons really isn't all that big by the time it is planted and waterways installed. I do have a 135 paludarium with a mix of aquarium fish such as small tetras, separated by glass from the terrestrial portion that contains some D. galactonotus, which has been ironically my very first tank and my most successful over all, well before I had any dart experience. I have all of the original darts and almost all of the original fish after 6 years. On the other hand, some interim experiments were near disasters. Introducing some red clawed crabs was definitely not the best idea, and the two crayfish were even worse, but fortunately the frogs avoided injury from these crustacian invasions from water habitat to the land portions where they crashed around like Godzillas destroying the jungle until I removed them.
Sometimes you have to make your own mistakes, and alas, I usually gone this route.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus