Question

Saddle back like lesions are seen in which infection?

• A. Furunculosis
• B. Aeromonas hydrophila
• C. Flavobacterium columnare
• D. Vibriosis

Hint:

"Saddleback disease" is a classic textbook synonym for columnaris caused by *Flavobacterium columnare*.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Columnaris disease is a common bacterial infection in freshwater fish, affecting both wild and cultured species.

Step 2: Detailed Explanation:
Columnaris is caused by the Gram-negative, gliding bacterium Flavobacterium columnare (formerly *Flexibacter columnaris*).
A hallmark clinical symptom of columnaris is the development of a pale or yellowish, discolored band around the body near the base of the dorsal fin, resembling a riding saddle.
This specific lesion has led to the common name saddleback disease.
The bacteria also cause fin rot, gill necrosis, and systemic infections under poor water quality conditions.

Step 3: Final Answer:
Saddleback-like lesions are characteristic of Flavobacterium columnare infection.