This fisherman’s soup is traditionally made by fisherman using small fish that were too small to sell at the markets, such as comber (hanos) scorpion fish (scorpions) and flying fish (helidonopsaro). These fish are often called "vrastopsara"; fish for boiling. Kakavia is the staple food for fisherman and is often made using sea water with fresh water added at the very end. Kakavia is derived from "kakavi" the word for copper pot that was used to make the soup.
You can also use filleted fish, however, for maximum flavour, whole fish are preferred. Some other recipes for kakavia use other types of seafood in including mussels and prawns, though I prefer to make it the traditional way using fish only. Hard, firm fish are best for this soup.