Question

Which is the most common bacterial disease in freshwater aquaculture?

• A. Columnaris
• B. Argulosis
• C. Ichthyophthiriasis
• D. Dactylogyrosis

Hint:

Columnaris → bacterial → common in warm water fish.

Answer 1

The Correct Option is A

Step 1: Columnaris is caused by Flavobacterium columnare.
Step 2: It affects gills, fins, skin — causes lesions, ulcers.
Step 3: Argulosis is parasitic (Argulus), Ichthyophthiriasis = white spot (protozoan), Dactylogyrus is monogenean parasite.

Answer 2

Cause-Type Sort: Sort each disease by its causative organism type — bacterial, parasitic, or protozoan — and match to 'bacterial disease.'

Columnaris, caused by the bacterium Flavobacterium columnare, is the most common bacterial disease in freshwater aquaculture, causing lesions and ulcers on gills, fins, and skin.

Argulosis is caused by a parasitic crustacean (Argulus), Ichthyophthiriasis is a protozoan (white spot disease), and Dactylogyrosis is caused by monogenean flatworms — all non-bacterial.