Apicomplexan groups infecting fish include primarily the Coccidiasina (eg, Eimeria spp, Hemogregarina spp). 5 Eimeria spp are usually enteric but may be extraintestinal as well? 3 Treatments for enteric coccidia are poorly reported but have included amprolium and nitrofurans. Sulfa drugs at antibacterial doses may also be effective. Successful therapy for apicomplexan hemoparasites (eg, Hemogregarina) is tinreported and can best be controlled by eliminating hematophagous invertebrate vectors.