As you may or may not know, almost all of the beasts in the Animal Kingdom (I'm still not sure about fish...it only stands to reason though) emit Pheromones, including humans. Although these trace chemicals are present and have a specific purpose, some species have evolved and no longer use them on a conscious level! This is usually due to the evolution of the sense of smell. Humans no longer use them as they did in "primitive days", however, studies have shown that the pheromones ARE used on a subconscious level to a degree. It is my theory (take it as you may) that fish, having a good sense of smell, do use pheromones on a conscious level. Thanks: Russell http://www.geocities.com/Heartland/Meadows/5335/index.html