silentbutdeadly
has some good things to say
It's usually an indicator of low levels of dissolved oxygen in the water...the cause of which can be many and varied.We had a stormwater creek on our property that we used to pump into an irrigation dam years ago, the water went like this in the creek and it killed all the fish in the dam after we had transferred the water, it was lucky that it was the end of the crop season as it killed the plants off also.