Abstract: A skeleton of fish consists of the vertebral column, jaw, ribs, cranium and intramuscular bones. It provides protection and control and also they produce red blood cells in addition to kidneys and spleen. Starting from the head, bony fish consist of solid hard bones called cranium. Cranium protects the brain from mechanical stresses. Osteichthyes have hinged jaws which aid them in feeding. But fishes like hagfish, lampreys are jawless fishes. Swim bladders help them to take up the dissolved oxygen from water and provide buoyancy. Otoliths are unique characteristics of ear plates of bony fish which helps in steadiness. Disease like Whirling disease destroys this steadiness. skeletal damage in fishes is also associated to be nutritional like Ascorbic acid (vitamin C) deficiency and Phosphorus deficiency. Bacteria (like Dissolving head disease) and Virus (Like Pike fry virus disease) also find their role in piscine skeletal pathology. Mycotic infection is also been observed in fishes skeleton. Exposure to range of toxicants negatively affect skeleton of pisces. Vertebral column fracture, associated with electrocution or lightning strike may break the spinal column at the flexure point. Understanding piscine skeletal pathology will pave the way to minimize economical losses due to unappealing appearance and explore new suitable remedials.

Keywords: Fish, Skeleton, Cranium, Bacteria, Virus.