The skeletal system of a goldfish is mainly to protect the goldfish, support its structure and leverage, and helps with its red blood cell production. A goldfish’s skeletal system is made of almost all small bones and cartilage and it barely has any big bones. The bones are made of almost all calcium. There are 3 main muscles in a goldfish’s muscular system, the tail and trunk muscles, the jaw muscles, and the fin muscles. In the tail and trunk muscles, there are myotomes which are muscles blocks and there are myosepta which are connective tissues that separate myotomes. The horizontal septum separates myotomes into two sections, ventral or dorsal. In the jaw muscles, the goldfish uses adductor muscles to close its jaw and abductor muscles to open its jaw. In a gold fish’s fin muscles, there are also adductor and abductor muscles. These muscles move a gold fish’s fins away from and close to its body. There are also erector muscles in the fins that help with the stability and flexibility of the fish’s fins.