Steve, the phytoplankton are microscopic plant life. The are the basis of the food chain. They are preyed on by zooplankton which are microscopic animals(bugs). The zoo's are fed on by a bigger bug and this keeps on going up the food chain until you put one in the skillet. So the green color of the water caused by phyto is a good thing; up to a point. It indicates a fertile pond. However, an overabundance of phyto could indicate an overly fertile pond. When that happens, the phyto blooms too much, consumes all of the dissolved oxygen and causes a die off. The biggest fish go first.

The perfect range of sight using a sechi disk is 18 to 24 inches. You can vary from that some either way. BTW, a perfectly clear pond indicates that the water is sterile and has trouble supporting life.

Make a sechi disk of some sort and check the real visibility. You may or may not have a cause to worry but it doesn't sound like a real dangerous situation to me.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa