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 tug the 1930s it became common to add a pilothouse amidship or near the stern, and to continue the cabin covering to the bow in what was known as a "sprayhood." Steel-hulled boats began to replace wooden-hulls in the late 1950s. Beginning in the 1970s, new regulations began to greatly restrict gill-net fishing, making the fish tug all but obsolete. The few fish tugs that remain in use today are largely objects of historical preservation efforts and not under commercial ownership. Fish tug A fish tug (sometimes called fishtug, fish tugboat, fishing tug, etc.) is a type of boat that was