Vetafarm Elasmo Tabs Large 1000pk. Elasmo Tablets are a multi-vitamin and mineral supplement for captive sharks and rays (elasmobranchs). In captivity we do not feed sharks and rays a completely balanced diet. Feeding frozen fish is associated with vitamin deficiencies. In closed systems with recirculated water there is a removal of many trace elements, especially iodine, which can cause thyroid pathology and disease in Sharks and Rays. These tablets enhance the health and longevity of captive fish by replacing any lost vitamins and minerals.