How do Fish smell and taste? (this has nothing to do with a BBQ!)

For a start fish have no tongues (where human tastebuds are found), most species have chemoreceptors which function as tastebuds on their faces and on other parts of their bodies. For example Goatfishes have chemoreceptors concentrated in the whisker-like barbels which project from their chins and which they use to probe the sand and mud for prey.

Catfishes also have "tastebuds" in their whiskers, allowing them to detect food in front, below and alongside them. Smell is a sensation, which fishes receive from water, which passes through their nasal passages. This is a vital sense for those species, which depend on scent for hunting (particularly at night

These fishes are equipped with long nasal grooves in their head for the passage of water, well-developed receptor cells and a large "smelling apparatus" in their brain. Moray eels hunt at night and are able to detect just a few molecules of an attractive chemical in the water. Their nostril openings protrude, tube-like at the front of their snouts, while the holes that the water exits are situated some distance back, next to their eyes.

Chemicals released into the water directly through a fish's skin or in its excrement may act as pheromones. These chemical signals transmit a variety of information i.e. species, sex, stress levels, readiness to mate, whether it is a member of a group, mate or stranger. Even information about its social status is conveyed. When water from the tank of a large "bullying" fish was experimentally introduced into the tank of fishes, which it had previously bullied, its former victims immediately reacted with apparent panic! It is thought that fishes on coral reefs smell their way around the reef, however this is difficult to prove.