Your tank looks like it will be fine for these leucs. Think about one thing, since one of them looks to be bordering on obese rather than merely female-- You may want to skip a day from feeding them now and then. This may just be an individual captive trait, however. I have 6 of them in an 80 gallon tank. 5 are slender, both male and females, but one is an real Idaho Butt--looks like she was raised on McDonald's fast food eaten on a couch in front of a TV set. She isn't as fast as the rest of them, so she is definitely not out-competing them for food, and seems otherwise healthy. While I like to keep my frogs a bit on the lean, mean, and active side, rather than stuffed couch potatoes, this is sometimes difficult to control with certain individuals in groups.
-----
Patty
Pahsimeroi, Idaho

Dendrobates: auratus blue, auratus Ancon Hill, tinctorius azureus, leucomelas. Phyllobates: vittatus, terribilis, lugubris. Epipedobates: anthonyi tricolor pasaje. Ranitomeya fantastica, imitator, reticulata. Adelphobates castaneoticus, galactonotus. Oophagia pumilio Bastimentos. (updated systematic nomenclature)