The genus name Tilapia is a Latin form of the word thiape, which means fish in Tswana. Tswana, also known as Setswana, is an African Niger-Congo language of the Bantu group. It is spoken by a majority of the population in Botswana.
The genus was named in 1840 by Andrew Smith, a Scottish surgeon, explorer, naturalist and zoologist. When in his early 20s, he was sent from Europe to Africa to supervise the medical care of European soldiers and soldiers of the Cape Corps.
In English, certain tilapias are known under the name "St. Peter's fish" due to their dotted pattern. In the New Testament, Jesus tells Peter, the apostle who would later become known as St. Peter, to catch a fish from the Sea of Galilee so that they can pay the temple tax. The fish turns out to have a shekel coin in its mouth. According to legend, the dots that can be seen on certain tilapias were caused by the fingers of Peter. Dark spots on the sides of the body are a common feature in several different tilapia species, including the one living in the Sea of Galilee: Sarotherodon galilaeus galilaeus.
Since tilapia is such an important food fish in Africa and the Middle East, many different languages have a name for it. It is for instance known as bolty (بلطي) in Arabic and amnoon (אמנון) in Hebrew. The ancient Egyptians who kept tilapia in ponds along the River Nile called the fish ỉn.t and had a special hieroglyph for it. On Gardiner's Sign List, a list of common Egyptian hieroglyphs compiled by the egyptologist Sir Alan Gardiner, the tilapia hieroglyph is number K1. The Egyptians used the hieroglyph for several different purposes and it would for instance denote the sound ỉn: when used as a part of a phonogram. When used as a logogram the hieroglyph only meant "a Nile tilapia", but when used as a determinative (ideogram) it could also refer to another important food fish, the flathead mullet.
When tilapia became a widely cultivated food fish in South-Eastern Asia, many local languages and dialects invented their own words for tilapia fish in general and/or for certain types of tilapia. In mainland China, tilapia is known as luofei (罗非鱼), a name based on the native home of the species Tilapia niloticus. In China, the River Nile is known as niLOU and the name for Africa is FEIzhou. In Taiwan, tilapia is instead more commonly known as Wu-Kuo (吳郭), a name based on the surnames of Wu Chen-hui (吳振輝) and Kuo Chi-chang (郭啟彰) who introduced tilapia to Taiwan by importing specimens from Singapore. While in Taiwan, you may also see and hear the name “South Pacific Crucian Carp” being used for tilapia. In Indonesia tilapia is known as ikan nila, while several other South-East Asian countries, such as the Philippines, call a large tilapia pla-pla while smaller specimens are known under the international name tilapia.
The genus tilapia was once much larger, but since then many species have been moved to the genera Oreochromis and Sarotherodon. Despite their new classification, it is still common to refer to them as tilapias in everyday speech, and all members of the tribe Tilapiini are correctly referred to as tilapiine cichlids.