Ornamental fish keeping has become an increasingly popular hobby, and there are now more than 330 mil lion ornamental fish sold each year throughout the world (Riehl and Baensch 1989). Although the total number of fish species exceeds 30,000 (Friede 1987), only 4000 of these species classify as freshwater or namental species (Riehl and Baensch 1989). Of these species a few hundred are popular a...