A rest platform, or "betta hammock" if you like, for my siamese fighting fish. I have a very high, upright tank as a center piece in our living room. Takio (as I named him after a Japanese warrior) was fine at first in the large water column, but his fins have gotten so large that I see him lounging about on any surface he can find and swimming seems to be quite impractical and cumbersome with such large fins. So I decided to make him a platform where he can rest at a comfortable distance to the surface for air.

I used one of the suckers from my heating element to stick the hammock onto the inside of the fish tank, so I hope you can use it with a sucker of your own - maybe just modify it if need be.