When I stocked my initial RES 9 years ago [600] I too had probably 50-75 morts that kept popping up for a week or so. Could have lost many more that I never saw. Keep an eye out and keep track of the number of morts you confirm. I imagine it's due to handling stress and not an indication of something amiss in the pond water itself [DO, pH, etc.] since you're not losing FHM or HBG. I would contact the hatchery and let him know what's going on, he should be willing to replace fish you're losing. How many RES morts now?

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

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