That's the most practical idea. An initial small tank can act as a kind of longer-term "quarantine" tank, where you can be sure all your frogs are eating, getting along together, healthy and for keeping track of their individual markings and personalities for awhile. After that however, I'm an advocate of "bigger is better" for most display purposes. With special uses, such as breeding select pairs, etc. it is also easier to keep track in a 10 gallon, but for four to six or so of the more communal darts, a 75 offers a lot of opportunity for creating a beautiful "mini-rainforest" with a nice variety of foliage, falls, waterways, etc.
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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