i was gonna post that link. isnt their more pics tho? i remember pics with rays
\found link:http://www.freshwaterstingray.nl/Frames Engels/English.html
go to mega tank then a tank but different.

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the thing is you whould have to be able to make a side be transparent for monster fish are to be seen from the side or they'll loose half the fun...my father inlaw decided to convert their swimming pool into a koi pond, he drained it all out, painted the bottom black and refilled it, biggest pond ive seen. deepest part of the pool is 10ft. not sure on how many gallons, but the pool is not small.