Dart Den

I have purchased two Dart Frogs, and last night I noticed both of them are pure black and they are dead. I had recently put crickets in there for them to eat. Is it possible that the crickets may have eaten/killed them. One just looked like it died standing there. Im not really sure what happened. Thanks for any help given.

1. What kind of dart frogs?
2. How long had you had them?
3. Did you have fecals run?
4. Pictures of the frogs and tank?

Lots of questions before anyone can help...

And unless you bought some P.terribilis, most Dart Frogs don't eat Crickets.

--Michael