Hello I have recently built a fish pond about 3 1/2 feet deep on the second shelf mb 800 to 1000 gallons or so. I had got 4 koi fish about 5" long or so they were hiding in a crease in the liner around were the pump is for awhile. But now I cant find them. I have checked the creases and dont see them anywhere. There are no rocks in the pond so theres really no were else to hide. The water is starting to get a little murky hut I dont know were else they would be. Does anyone have any suggestions??