Here's the B Cody advice from Feb 2015 in this link:
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=402127Here are some pretty standard guidelines for water temperature differences when stocking fish.
Before stocking fish in a pond, adjust the water in the transport tank holding the fingerlings to match the pond water in temperature and other water quality factors such as pH, alkalinity, and hardness. This can be done by putting small quantities of water from the pond into the transport container (called tempering), so that the container water is eventually similar to that of the pond usually within 5F.
As a general rule, most fish can withstand a 5 degree F change in temperature without severe stress and a 10 degree F change if the water is tempered over a period of 30 minutes. For greater temperature differences, care must be taken to slowly equalize water temperatures before moving the fingerlings from the container to the pond. In this case, adjusting water temperature 1 degree F every 10 minutes is a good rule to follow. Tempering is especially important if fish are going from cool water to warm water.
Insufficient tempering can kill the fish by temperature shock or shock from other water quality factors. If the fish are not killed by the shock, they can be weakened, which lowers their resistance to disease.
