High turbidity is the leading cause of summer fishkills. (High turbidity is less than 6" of water clarity.) In summer cases, a low-pressure weather pattern will trigger the pond biology to crash overnight. American Shad will comprise at least 95% of the fish affected here. The second cause of dead fish is an irregular turnover from weather events (e.g. a low-pressure storm). In this case, the bottom strata devours the oxygen in the whole pond. IF your pond "flips"... you can expect some die-off. Expect to see various species of fish. The third phenomenon is called Winterkill. Our aeration provides 24/7 protection against all fishkills.