Thanks for the replies. I think the weather temps are condusive since several other ponds in the immediate area have mayflies present. The issue with this pond is no readily source of electricity without alot of cost, although it is feed by 5 springs constantly so I am hoping this may help with oxygen, I will test soon. Pond was drained and filled and restocked last year , but there were no mayflies present that year either. Assuming the environment were suitable , what is the procedure to establish mayflies.