Aphids from UNSPRAYED fruit trees, peas, cabbage, etc. are a real treat to many of the darts. Just pluck a leaf and put it in their tank. The aphids are relatively plant genus or species specific, so will not infect your vivarium plants. My galacts, leucs, auratus in particular, will gather around and lap up aphids from a leaf full of aphids. It's always worth a try. If the darts do not happen to take to them, just remove them leaf and all after a few hours. But in my personal experience, they pig out on them. although I've never actually tried them with my thumbnails and pumilios that I can recall. I believe they should be considered more as a varietal treat than a mainstay diet, since they can't be conveniently dusted, etc. for better vitamin/calcium control. Some species contain a lot of sugars, which may be like eating too much cake with frosting, if over-done.
The mixing question answer is generally "no," don't mix any two genera or species--with exceptions perhaps, based on some long- time experience. My advice has always been, just don't try it until you've raised each species you are considering separately for a few years. I have never tried to do this because I find the individual species challenging and interesting enough in separate vivariums. It is done by some people, and apparently done successfully, however.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
7 D. imitator
6 D. leucomelas
4 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