Which of the following causes ich disease?

Correct option is A

Correct Answer: (a) Ichthyophthirius multifiliis
Explanation:
→ I. multifiliis causes freshwater ich (white spot disease), a major parasitic disease in aquaculture.
→ Characterized by white cysts on skin, gills, and fins.
→ Highly contagious and can cause mass mortality.
Information Booster:
→ Life cycle includes infective theronts and protective tomonts.
→ Stress increases susceptibility.
→ Salt treatment, formalin, and temperature manipulation are common controls.
Additional Information:
(c) Cryptocaryon irritans causes marine ich, not freshwater ich.