any item of livestock needs acclimatising when it goes in a tank, even plants! (but thats for real special plants, the ones sold are generally hardy)
take it from me however that frogs are very boring! you never see them, even at feeding time and you go about thinking they have died or jumped out..... until you do a water change and move some things around, then you see it.
have you ever thought about shrimp? they are surprisingly active and quite busy. if you can get hold of say 6-10 cherry shrimp you would get a lovely colony going.
but by the gods dont introduce them when you tank is in a state.. i'd suggest leaving the tank a good 5 weeks before introducing anything like that.
cherry shrimp were my favorite, lovely red colour and easy to see.
i do have a bamboo shrimp in my tank. she is out all the time. sits on top of the thermometer fanning the water for bits of food. ill see if i can get a picture of her..
heh win

lovely thing, sits on your finger if you hold it under the water when feeding.
bamboo shrimp are a little larger than cherry shrimp