Role of nutrients in skeletal metabolism and pathology in fish — An overview

The development of skeletal disorders in larval and juvenile fish is linked to a poorly understood relationship between nutrition, environment and genetic factors. These disorders are often a complex mixture, including vertebral and spinal malformations. In marine fish hatcheries, neck deformities, and vertebral and spinal disorders are most abundant. Fish bones are found in all shapes and sizes. They have a wide diversity of cartilages and bones with chondro- and osteogenic cells. Bone and cartilages may develop during embryonic, larval, juvenile or adult stages under normal ontogeny as well as during pathological states, wound repair and bone regeneration. Three types of cells play a significant role in the bone remodeling process and bone formation, resorption and mineralization; osteoblasts (bone forming cells), osteocytes (entrapped inside the bone matrix), and osteoclasts (multinucleated bone resorbing cells).Unfortunately, limited research effort has been directed to characterize the pathological changes associated with disorders linked to nutrient deficiencies in fish. Fish contain a significant amount of lipid and micronutrients in skeletal tissues including collagen, which are particularly susceptible to lipid peroxidation. A brief review of the current state of knowledge on the role of key nutrients in the pathogenesis of skeletal deformities with an emphasis on minerals (calcium, phosphorus and trace elements), vitamins (A, D, C, E and K), lipid and nutrient interactions is presented. Bone deformities associated with nutrient deficiencies and toxicities in various fish can provide an excellent model to study gene action, cell differentiation, morphogenesis, species differences in phenotypic expression of genetic abnormalities, deposition of calcium, phosphorus and other trace elements in cartilage and skeletal tissues in response to vitamins and hormones and nutrient interactions.