A big fish kill north of Algona is blamed on the snow. Department of Natural Resources environmental specialist Scott Wilson says anglers alerted the area county conservation board, which notified his office in Mason City. Hundreds and perhaps thousands of fish that have died, he says, for several miles along the river both to the north and south of Algona. Wilson says fish breathe underwater, but these fish…drowned. Wilson says oxygen levels in the river were already low, and when a thick blanket of snow cut off the last of the sun to the vegetation, the fish died, starved for air. Wilson says the fish breathe all the oxygen and then it’s gone, and with low DO levels — Dissolved Oxygen — some of the larger game fish probably started dying a week ago. It’s not the end of the world, Wilson says, and not an extremely serious problem, though he expects there will be similar fish kills in other parts of the state. Wilson says nonetheless, anybody who finds a fish kill is asked to report it to the D.N.R. Even when they know it’s probably a case of low oxygen, specialists go out and check the water for things like oxygen levels, and also ammonia. That could signal a feedlot pollution spill, and its absence can help confirm a fish kill was indeed caused by low oxygen.