Lake Tanganyika is very rich in fish species. It is exploited by fishermen but also by fish-eating birds often considered to be competitors of man. This osteological study was undertaken in order to set up a methodological tool that would serve as a basis for studying the diet of ichthyophagous birds. Fish were collected, grouped by family. They were then taken to the laboratory in order to extract cranial bones characteristic of each species or genus. A key to identify these bones was made based on the similarities and differences between these bones. Correlations between the length of the characteristic bones and the size of the fish have been calculated.