Bradford experts have found something fishy in the remains of the ruined Roman city of Pompeii.

A team of archaeologists from the University of Bradford, who are helping to excavate the ruins, are delighted by the major discovery of a whole fish skeleton.

They say the sardine-sized fish - the first intact one to be discovered at the dig - highlights important differences between how rich and poor Pompeians lived their lives.

Analysis of tiny traces of bones and seeds have showed the rich feasted on expensive fish - and the team is currently examining six fish storage tanks.

They date back to the second century BC, and are believed to have been used to create a fish-based sauce called Garum, a favourite of the affluent.

The pungent sauce - used as a condiment - is thought to have been made by leaving fish to rot in salted water and the team is carrying out further tests in Bradford to confirm the theory.

The fish skeleton was found in the residue of one of the tanks and is now being studied by Dr Andrew Jones, lecturer in Archaeological Sciences at Bradford.

"To find a complete fish like this is exciting," said Dr Rick Jones, of the university's archaeology unit.

"It means we can move on a step in understanding what people were actually doing in the city. The tanks we've found along the street were all built at the same time, then they go out of use, also at the same time. Whatever exactly it was they were doing, was suddenly stopped."

He added: "In this part of Pompeii we are dealing with some of the richest people of the city. They extended their home to take over what had been three or four small houses, while the poor were squeezed into living in small shops and workshops.

"Because fish rots so quickly it becomes expensive. It was the food of the rich."

The project is building a deeper understanding of the society of the ancient city, revealing how it developed over five centuries. There is clear evidence of sharply rising social inequality from first century BC.

"All our studies give a picture of rapidly changing social dynamics, as the gaps between rich and poor became more sharply defined," Dr Jones said. "One sign of this was who got to eat fresh fish and who didn't."