Edited sentence: As soon as the fish enters freshwater, the fish undergoes a natural deterioration of its flesh, and the scales become duller as time goes on.The fish is then considered dark, and because of the deterioration of flesh, the meat is generally considered to be of low quality.When a salmon is ocean-caught or caught just after it has transitioned from ocean water to a coastal estuary, the salmon is known as being "bright," meaning that the fish is silvery and its scales are shiny.When the salmon is bright, the meat is usually in good condition and exhibits a healthy orange or reddish hue