Eels were a popular food among wealthy Romans, but a number of Romans seem to have really loved their pet eels. The orator Quintus Hortensius was very fond of the eels which he kept in the fishpond of his villa, he is reported to have wept when one of his eels died. This was probably a moray or conger eel, since they are the only eels which have pectoral fins that earrings could be attached to. I am not sure what he meant by that, since the ancient Egyptians had been raising fish in ponds for centuries. Pliny the Elder said that it was C. Hirrius who first used fishponds solely for the raising of eels.
Eels are especially well suited to being raised in artificial ponds.
Ponds in which eels are raised can be stocked more densely than with any other species of fish. Larger eels will prey on smaller eels, as well as other fish, so eels of different sizes and ages are usually kept separate from each other in modern ponds. The ancient Romans probably also did this. Many Roman fishponds contain tanks which would be perfect for raising fish that would eat each other if they had to share a pond. In my article about the saltwater fishponds of ancient Rome , I mentioned that amphorae have been found embedded into the walls of a number of Roman fishponds.