Thanks Bill for your response. I may try to use one of my 1/4 ac pits to stock with some koi to see what will happen in my situation in these clear water gravel pits. The reason I ask this question is part of my project is to build a waterfall and 300' of stream bed lined in 45 mil rubber recirculated by a 8-10,000 gal/hr pump up some 12' of head. The course will have 2-3 pond for fish . My wife likes the sound of running water and the enjoyment of feeding these colourful fish up close to the house. The result I'm such is that some of these fish will wash down the stream and into the lake even if I put wire mesh across the stream mouth. Any thoughts......

Rowly