I work at a park, and we have a 1.5 million gallon pond that houses Japanese Koi and goldfish. when the pond was installed the park management opted not to install a filter system, and now 7 years later itd be very difficult ( and more expensive ) to retrofit some mechanical filtration into the pond. what we are looking for is some kind of bio-logical replacement. we had catfish but either they died or are just in effective. at this writing the pond is undergoing a cleaning and will have fresh well water pumped in. I’m thinking maybe some snails,but not sure if the fish will eat all of them ( they’re swimming pigs ) i have also considered some other algae eater fish. temperature in the water usually hovers around 55, and the deepest section of the pond drops to 4 feet so the fish will have somewhere to go to for the occasional cold day. we’re in central Florida, so most fish are available. so any suggestions regarding fish are feasible
