I've heard of people doing this and i was wondering what anyone else thought.My kids get buckets and play in the gravel rocks that are in our driveway.There are about 5 small buckets full in my yard as we speak.These are more natural rocks with shades of white,tan, cream and various shades of brown.I was wondering if they could be used in a fish tank.lol, they look like the same type of rocks that are sold in the lfs.And i would have to buy about 4 diffrent bags of tanbk gravel to get those color variations.So, basically, if i got some gravel rocks, washed them REALLY well and maybe allow them to soak...could they be used in a fish tank? lol, just curious.