Will, welcome to Pond Boss. The answer to your question is yes. But, it exists in all ponds and is called a thermocline. Fish can go there but not stay very long. It is essentially storage that becomes usable when evaporation occurs and sunlight penetrates previously dark areas. Wind action and sunlight oxygenate the previously unusable areas.

Last edited by Dave Davidson1; 02/25/18 08:44 AM.
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