Question

Which of the following is a bacterial disease of salmonid fishes?

• A. Whirling disease
• B. White Spot disease
• C. Enteric red mouth disease
• D. Gas bubble disease

Hint:

Salmonid health is a major part of coldwater fisheries. Remember: Yersinia ruckeri = Enteric Red Mouth (ERM). It is often controlled through vaccination in commercial trout farms.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question requires identifying which of the listed conditions is caused by a bacterial pathogen specifically in salmonid fishes (trout and salmon).

Step 2: Detailed Explanation:

• Enteric Red Mouth Disease (ERM): This is a serious bacterial infection caused by Yersinia ruckeri, a Gram-negative rod-shaped bacterium. It is named for the characteristic hemorrhaging (redness) it causes in the mouth and throat area of trout. It also causes systemic septicemia and inflammation of the internal organs.

• Whirling Disease (Option A): This is a parasitic disease caused by the myxozoan Myxobolus cerebralis. It affects the cartilage of young salmonids, causing them to swim in a "whirling" motion and often results in skeletal deformities.

• White Spot Disease (Option B): As discussed in the previous question, this is a protozoan parasitic disease caused by Ichthyophthirius multifiliis. It affects a wide range of freshwater fishes, not just salmonids.

• Gas Bubble Disease (Option D): This is a non-infectious, environmental condition (abiotic). It occurs when water is supersaturated with gases (usually nitrogen or oxygen), causing gas bubbles to form in the fish's tissues, blood, and eyes.

Step 3: Final Answer:
Enteric red mouth disease is the bacterial disease of salmonids among the choices.