Cushitic Fish Taboo
Among the Somali people, most clans have a taboo against the consumption of fish, and do not intermarry with the few occupational clans that do eat it.
There are taboos on eating fish among many upland pastoralists and agriculturalists (and even some coastal peoples) inhabiting parts of southeastern Egypt, Ethiopia, Eritrea, Somalia, Kenya, and northern Tanzania. This is sometimes referred to as the "Cushitic fish-taboo", as Cushitic speakers are believed to have been responsible for the introduction of fish avoidance to East Africa, though not all Cushitic groups avoid fish. The zone of the fish taboo roughly coincides with the area where Cushitic languages are spoken, and as a general rule, speakers of Nilo-Saharan and Semitic languages do not have this taboo, and indeed many are watermen. The few Bantu and Nilotic groups in East Africa that do practice fish avoidance also reside in areas where Cushites appear to have lived in earlier times. Within East Africa, the fish taboo is found no further than Tanzania. This is attributed to the local presence of the tsetse fly and in areas beyond, which likely acted as a barrier to further southern migrations by wandering pastoralists, the principal fish-avoiders. Zambiaand Mozambique's Bantus were therefore spared subjugation by pastoral groups, and they consequently nearly all consume fish.