How do fish get ich and what are the common symptoms associated with this parasitic infection?

Fish get ich, also known as ichthyophthiriasis, from a parasite called Ichthyophthirius multifiliis. This parasite is commonly found in aquariums and can infect fish through contaminated water. Common symptoms of ich in fish include white spots on the skin, flashing or rubbing against objects, increased mucus production, and respiratory distress.