Of the host anemones, H. crispa, E. quadricolor, and H. magnifica are home to the greatest number of species of clownfish (~10 or 12 species of clown each). Some clownfish are found only in one species of anemone in nature, e.g. tomato and maroon clowns are found only in E. quadricolor. If you want a good reference for exactly which species goes with which host, Joyce Wilkerson's book "Clownfishes" is good and so too is Fautin and Allen's "Anemone Fishes and Their Host Anemones."
