Is there something in the tank that could be killing your fish and frogs? A disease perhaps? If your frog died in the tank from something then the fish and other frog would have eaten it or it could have been stages of decomposition. My friends mouse died and she didn't find it for a week (she clearly never cleaned) and when she found it the other two mice had eaten it completely, nothing but bones.
As for ADF's with betta's it depends on the betta's and frogs. My boys get along just fine and even sit in the gravel side by side. Never had a fight nor a tail nip but they enjoy spending time together. Since my frog was moved to a hospital tank for chystrid fungus my betta has been eating his tail to a stump from the stress of losing him but I'm getting him shrimp as a temp tank mate until Bilbo can live with him again.
In any community tank the fish will eat their dead. I have seen this with everything from platys to goldfish. Once a fish dies or even gets too sick to move it's food.
Last edited by LadyVictorian; 10-22-2012 at 01:30 PM.