Convict cichlid fish scale, SEM

Coloured scanning electron micrograph (SEM) Convict cichlid fish scale with growth rings (Cichlasoma nigrofasciatum, formerly known as Archocentrus nigrofasciatum). Convict cichlids have ctenoid fish scales. As the fish grows the fish scales grow with a pattern of concentric growth rings. These growth rings increase in number with the scale size and appear similar to those found in the cross section of tree trunks. In some cases, ctenoid scale growth patterns are utilized to determine the age of a fish. Fish scales are dermally derived, specifically in the mesoderm. This fact distinguishes them from reptile scales. Scales protect the body from outside dangers such as predators and infection. Not all fish share the same kind of scales. Fish scales are covered with fish skin, a fine layer of epithelial cells. Magnification: x50 when shortest axis printed at 25 millimetres.