Figure 4
From: Columnaris disease in fish: a review with emphasis on bacterium-host interactions
Skin ulceration (arrow) in a minnow ( Phoxinus phoxinus ) caused by F. columnare. The lesion has progressed into deeper skin layers, exposing the musculature. The edge of the ulceration displays a distinct reddish tinge and its centre is covered with yellowish-white mucus (bar = 1 cm).