Just a little more explanation :/
The bullfrog was going to be killed in a petstore, she was a "mystery tadpole"
and instead of letting her die I volunteered to take her.
After they knew she was a bullfrog they didn't expect anyone to want her.
I guess that is an "impulse buy" but I couldn't stand the way
they were talking about her.
I was doing research since then and working on a larger and
very bullfrog-friendly tank than her temporary one.
It was about 2 days before I could get her moved that she died 
I have FBTs that were also given to me with no warning, as a
Christmas present.. but I was told several days before I got them,
so I did as much research as I could before then, they are thriving
in their second (prepared by me) tank now.
Lastly.. she wasn't "stuck" in a corner really.. sorry if
I made it sound that way.. I don't think it was possible for
her to be stuck anywhere in that tank, it was pretty much
danger-free in that regard. The corner was roomy enough
for her to spread out all her limbs, and easily jump out of,
but it was on the side of the filter so that the current
wouldn't bother her so I thought she was just trying to
escape the current (poor thing.. I think that underwater
filter was the WORST thing I put in that tank..) and thought
she was safe.. I would never have left her stuck somewhere 
I didn't think I was leaving her in a bad situation at all..