The bioload is Incredingbly SOOO HEAVY. What's your water change schedule ?
I would absolutely take a water sample right before you do a waterchange, then bring it to the LFS, so they can test your water for ammonia/nitrites.
Also, on the pictures, your water look white cloudy, wich could be caused by a bacteria bloom, wich only occur when tank have cycle problems... You need to test theses params absolutely: ammonia and nitrites.
Also, what's your water temperature, do you use a heater ? This is a cold water frog... So you don't need one.
I would increase your filtration too. Aquatech 20/40 means it's made for a normal bioload 20 gallon tank. So I would increase to a filter that can hold much more filtration, like a fluval C4 instead... Remember, 20g tank can hold 2 goldfish only with a lot of filtration (40g filter like yours). Each frog you got is almost a goldfish x10 in term of bioload...
And you didn't awnser my last question, do you clean the filter bio media under the tap water ? Or change them often ?