Fish intelligence in paradise fish ("Macropodus opercularis") which avoid places where they have experienced a single attack by a predator and continue to avoid for many months. A number of studies have shown that fish can retain information for months or years. Anecdotally, channel catfish ("Ictalurus punctatus") can remember the human voice call announcing food five years after last hearing that call. Goldfish remember the colour of a tube dispensing food one year after the last tube presentation. Sockeye salmon still react to a light signal that precedes food arrival up to eight months since the last reinforcement. Some common rudd and
Fish disease and parasites mid-1980s, in particular, an overview report which states that "the fish that have the longest fresh water residence time as juveniles have the most noticeable infections. Hence in order of prevalence coho are most infected followed by sockeye, chinook, chum and pink." As well, the report says that, at the time the studies were conducted, stocks from the middle and upper reaches of large river systems in British Columbia such as Fraser, Skeena, Nass and from mainland coastal streams in the southern half of B.C. "are more likely to have a low prevalence of infection." The report also states "It