christ....lol i would fill it up with salt water and get a dolphin.. J/K
yo so anyways... dude that is ridiculous.... unless you are going to put on snorkel and dive with your fish, i would rip that thing down and build a nice little pond.... the only reason i say this is because i think you will enjoy it more in the ground and can get into different plants, etc... there is no windows on the side so u will be peaking over...LAME!! if the liner is good to use you have free liner, so start digging!!
although... if you build a deck around it and put big bolders and plants, that could be one sic above ground unit... but only if it's done right!! if your just going to stock it and call it a day, i would rip it down... just my opinion though and it's what ever makes you happy!! good luck!! and take lots of pictures please....