Here's the response I got from Richard Ott of TPWD in Tyler:

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Hey Paul, it’s good to hear from you again. The crappie in your photos exhibit a disease called Columnaris. Columnaris results from an infection by the bacteria (Flavobacterium columnare). The red eroded area in the center of the lesion is from the bacteria and the white foamy area around the central lesion is a secondary fungal infection. The disease is endemic in nearly all fish populations and manifests itself any time the fish’s immune system is suppressed from external factors such as rapid temperature change or spawning stress. Frequently the lesions occur where the fish has been previously handled and the slime was rubbed off (this is why it is always better for the fish to handle it with wet hands). Although the disease is contagious between fishes it is not harmful to humans – the fish may still be eaten if properly prepared. It is also a disease that is more common when fish are crowded together or when numbers are high. This is one of natures ways of keeping populations in balance.

[FONT='Arial','sans-serif']Generally fish are not so stressed by the disease that they stop feeding (obviously if you caught it). As long as the fish continue to feed they usually are able to recover.

With your permission I would like to include your photos in my library of fish disease images.

Richard A. Ott, Jr.
Natural Resources Specialist VI
Inland Fisheries District 3C – Tyler