Thanks !! It's roughly 2500 gallons or so. I did not build it personally, I had a local guy here do it for me. It has a aquascapes waterfall box concealed in the berm, with a skimmer box on the other end. I have a 1600 hydrive pump for the waterfall. It has low voltage lighting with three bulbs hidden in the rocks. I have a shelf in there about 1 ft down on one side , so fish can hide underneath . I have roughly 13 fish or so in there 5 of them have been with me for years, others were born in the pond. Because the pond has so many nooks and crannies in the rocks I get lots of koi babies, I have to give away the undesirables so it does not get overstocked. I only put microbe lift in it, I never use any chemicals. I have various Lilly's and plants every year and I always have 2/3 of the pond covered in floating plants to cut the sun in summer. It's pretty self sufficient once the bacteria gets going.