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
What is a Masterpiece? confluence of memories and emotions forming a single idea", that it has "a power of recreating traditional forms so that they become expressive of an artist's own epoch and yet keep a relationship to the past". The highest masterpieces are said to be "illustrations of great themes." Clark also implicitly excluded the erotic from considerations of what constituted a masterpiece, based on his perspective that a necessary condition is the balance between sense and form (works that are too sensual are, therefore, unbalanced and not to be categorised at masterpiece level). What is a Masterpiece? What is a Masterpiece? is