Hey also from a big time Discus guy he swears by this don't know if it's totally safe for rays or not and i am not possative on spelling But here goe's (Vermosil) also used for internal parisites in birds comes in powder form talked to this guy quite often when he is on the forum pm wise he swears Prazi and others don't come close to killing all internals but this stuff does ...One thing they will stop eating while treating so definatl a danger that way but something to consider ...