Unfortunately, fish are not immune from cancerous growths. And sharks, being fish, are included in this group. Like tumors in all other species, some are treatable, while others are not. Some of the most common cancers we seen in daily practice include: Goldfish Infiltrative Papilloma-Like Warts; Hikui in Koi; Chromatophoromas in Koi and Goldfish; Gonadal Sarcoma and others. To find out more about these and other tumors visit the Aquatic Veterinary Services webpages.