Fish plays a useful role in a healthy and balanced diet. Polyunsaturated fatty acids (PUFA), more specifically omega-3 fatty acids, exert a positive effect on the cardiovascular and nervous system. They also play a key role on the development of the neonates brain and their visual development. Due to these beneficial characteristics, the demand of PUFA concentrates has recently increased and, consequently, the industrial interest on the production methods. Fish oil has traditionally been used as the main source of PUFA. This book provides a comparison among physical and enzymatic techniques for getting omega-3 concentrates from fish oil. It also aims to resume the proximate composition (i.e. lipid, protein, humidity and ash content) of the main discarded species in the Mediterranean Sea; examines the role of fish oil and omega-3 fatty acids in the mitigation and treatment of traumatic brain injuries; and discusses the long-term cardiovascular effects and safety of fish oil among women with diabetes and their infants.