Banding Patterns and Coloration

The main cultured species of tilapia usually can be distinguished by different banding patterns on the caudal fin. Nile tilapia have strong vertical bands, Blue tilapia have interrupted bands, and Mozambique tilapia have weak or no bands on the caudal fin. Male Mozambique tilapia also have upturned snouts. Color patterns on the body and fins also may distinguish species. Mature male Nile tilapia have gray or pink pigmentation in the throat region, while Mozambique tilapia have a more yellow coloration. However, coloration is often an unreliable
method of distinguishing tilapia species because environment, state of sexual maturity, and food source greatly influence color intensity. The ÒredÓ tilapia has become increasingly popular because its similar appearance to the marine red snapper gives it higher market
value. The original red tilapias were genetic mutants. The first red tilapia, produced in Taiwan in the late 1960s, was a cross between a mutant reddish- orange female Mozambique tilapia and a normal male Nile tilapia. It was called the Taiwanese red tilapia. Another red strain of
tilapia was developed in Florida in the 1970s by crossing a normal colored female Zanzibar tilapia with a red-gold Mozambique tilapia. A third strain of red tilapia was developed in Israel from a mutant pink Nile tilapia crossed with wild Blue tilapia. All three original strains have
been crossed with other red tilapia of unreported origin or with wild Oreochromis species. Consequently, most red tilapia in the Americas are mosaics of uncertain origin. The confused
and rapidly changing genetic composition of red tilapia, as well as the lack of “head-to-head” growth comparisons between the different lines, make it difficult for a producer to identify a “best” red strain. Other strains of tilapia selected for color include true breeding gold and
yellow Mozambique lines and a “Rocky Mountain white” tilapia (a true breeding line originating from an aberrant Blue tilapia, subsequently crossed with Nile tilapia). Most
strains selected for color do not grow well enough for food fish culture. Identifying the species of an individual fish is further complicated by natural crossbreeding that has occurred between species. Electrophoresis is often used to determine the species composition of a group of tilapia.

SRAC Publication No. 283
Thomas Popma1 and Michael Masser2
March 1999