I would say this is a variable answer. It depends on the age of the frogs and the size of the tank. Having large amounts of uneated flies in a small tank can definitely stress a frog. I would say feed all they can eat in 15 minutes and just a little extra. This won't be a number of flies, but rather an estimate by volume. I could never tell you 15 flies per frog per feeding-- it just depends. When the frogs mature, and if you have a large enough tank, you can reduce the frequency of feeding, but increase the quantity. Back in the day, I had D. imitator, E. tricolor, and D. auratus in a 90 gallon tank and I fed that once a week. I sprinkled about 1.5" worth of flies in a regular deli cup across the tank, and had little medium cups in there for them to congregate towards. Via that method they could feed as they wished.
J
