Puberty is the development period covering the transition from an immature juvenile to a mature adult reproductive system. The initiation of puberty in males is marked by the onset of sperm production and in females by the onset of egg production. Under farm conditions some species (e.g. cod, sea bass, salmon) enter puberty precociously, leading to decreased flesh quality and growth performance. Early sexual maturation is considered to be one of the greatest problems in fin fish culture.