Question

The white spot disease is a common disease of freshwater carps and is caused by

• A. Trichodina sp
• B. Costia necatrix
• C. Ichthyophthirius multifilis
• D. Mixobolus catlae

Hint:

Always distinguish:
- White spot disease of *shrimp* = Viral disease (WSSV).
- White spot disease of *freshwater carps (Ich)* = Protozoan parasite (Ichthyophthirius multifiliis).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Fishes are prone to parasitic infections from protozoans, which can proliferate rapidly in high-density pond environments and cause severe epidermal damage.

Step 2: Detailed Explanation:
The freshwater "Ich" or white spot disease is a highly common parasitic infection of freshwater carps.
It is caused by the large, ciliated protozoan parasite {Ichthyophthirius multifiliis (noted as Ichthyophthirius multifilis in the paper's option).
The parasite burrows into the epidermis of the fish's skin and gills, appearing as small, visible white salt-like spots.
It causes severe irritation, excess mucus production, and respiratory distress.

Step 3: Final Answer:
The white spot disease in carps is caused by Ichthyophthirius multifilis, which corresponds to option (C).