What are common signs of Columnaris infection in fish?

Columnaris infection, caused by the bacteria Flavobacterium columnare, often presents with a range of clinical signs in fish, particularly affecting their gills and skin. The presence of yellow-white or dark brown gills is indicative of the infection's impact on this vital respiratory organ. Infected fish may also exhibit severe lesions on their gills, which can lead to breathing difficulties and ultimately affect their overall health.

This discoloration of the gills is due to necrosis and sloughing of the epithelial cells resulting from the infection, and it can severely compromise the fish's ability to extract oxygen from the water. Fish with affected gills may show signs of distress, such as gasping at the water's surface or exhibiting lethargy.

While other choices may present symptoms associated with fish stress or disease, they do not specifically relate to Columnaris infection or are not commonly linked to it. Head shaking and erratic swimming may be signs of multiple issues, such as stress or other infections, but they are not hallmark signs of Columnaris. Increased appetite and growth are typically contradictory to an infection, as infected fish often lose their appetite and do not thrive. Lastly, fuzzy patches on skin suggest other diseases, such as fungal infections or certain proto