Stressed fish probably from low dissolved oxygen or an overmixing and subsequent chilling of the lower water column if you over did it with a diffuser(s). If it doesn't cover too much of their bodies they will make it once the water warms up, they start feeding, and their immune system kicks in.
Also catch and release ice fishing can bring on fungal issues from handling.
When fish are stressed they more easily succumb to fungal and bacterial issues just like stress can more easily bring on a cold in us.
Last edited by Cecil Baird1; 02/23/14 04:25 PM.
