Excuse the extra post but I misspelled the name in my previous message. Anyway, Ich is more common in coolwater and warmwater fish (like Bass and Catfish) than in coldwater fish like trout. Also it doesn't spread as well in streams and rivers as it does in ponds, because it tends to get lost in the current. Its OPTIMUM temperature (for best reproduction) is said to be 25 degrees C, 77 degrees F. Steev