A Knifefish's appearance and swim behavior make them very unique and desired. Yet, none can compare to the Glass Knifefish’s almost transparent appearance. They look like they are swimming in slow motion and they do so by moving their fins in a wave like motion that looks like a skirt. In the wild, males compete for a female’s attention by sending out low frequency electric charges. They are a shy fish that will spend most of their time hiding, but when they are out and about this knifefish will put on a show. The Glass Knifefish is a peaceful fish that can be kept a school or with other fish of the similar size and temperament. Be sure the aquarium is large enough and has enough swimming space because males can grow up to 17 inches.