Sergius Orata (fl. c. 95 BC) was a famed merchant and hydraulic engineer of the Roman Republic.

Sergius was well-known by his contemporaries because of the breeding and commercialization of oysters, for which he was an innovator. Orata wanted to take advantage of Romans' liking for shellfish as food, so he developed a new system for breeding oysters. He constructed channels and preys to control sea tides, as well as high vaults over Lucrine Lake in Campania.

He was also credited by Vitruvius with the invention of the hypocaust (underfloor heating), although this is not fully confirmed. What seems certain is that he invented a type of hanging baths ("balneae pensiles"), some kind of relaxing thermal baths; they are usually considered to be hypocausts. He commercialized them as successfully as the oysters. He used to buy villas, construct the baths, and then resell them at greater prices.

Romans said of Sergius that he could breed oysters on the roof of his house. Sergius Orata became rich due to his inventions; he was distinguished for his love for luxury and refinement. "The orata," Festus noted, "is a kind of fish so called for its golden color (aurata, "golden," also spelled orata). ... Because of this, it's said about the very wealthy Sergius that they called him orata, because he wore two big rings of gold. Some authorities assert that his nickname just comes from the commercialization of those fishes."

References [link]

• About Roman baths (referring to Sergius Orata), by William Smith.
• Holland, Tom. (2003). Rubicon. 
• Sergius Orata: Inventor of the Hypocaust?. Fagan, Garret G.
• About Sergius