Final answer:
The characteristic symptom of ich in fish is the presence of white dots on the body.
Step-by-step explanation:
The characteristic symptom of ich in fish is the presence of white dots on the body. Ich, also known as white spot disease, is caused by a parasite called Ichthyophthirius multifiliis. As the parasite infects the fish, it forms small white cysts on the body, fins, and gills.
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