In times preceding these infatuated extravagant ages, the purpose for which vivaria were first created was steadfastly kept in mind and wonderfully advanced by practical pisciculturists. From being a mere pond for keeping fish alive till needed for the table, vivaria developed in the course of time into spawning grounds.
The pisciculturists went even farther. They turned lakes and rivers into natural vivaria by depositing in them not only adult fish, but the spawn of all such species as are in the habit, although born at sea, of pushing some distance up estuaries and streams. Columella instances specially the rivers Velinus, Sabatinus, Ciminus, and Volsinius as examples of the great success of this experiment in fish propagation.[557]
Comacchio on the Adriatic, from its extraordinary advantages of position and of fish-food, can hardly have escaped being utilised for similar purposes by the Romans. For many centuries, at any rate, its valli or breeding grounds have been renowned. Ariosto sings its speciality:
“La Città che in mezzo alle piscose Paludi del Pô, téme ambe le foci.”
Tasso hands it down as the place where the fish—
“finds itself within a prison swamp Nor can escape, for that seraglio Is aye to entrance wide, to exit barred.”
At the present day over twelve hundred tons of fish, eight hundred of them eels, are annually captured at Comacchio.[558]
Since the above was printed, new and interesting evidence of the importance of fish, not only as an economic, but also as a hygienic, factor in the nation’s prosperity has been furnished by Prof. J. A. Thomson in his lecture before the Royal Institution, January 6, 1921.
He traced a connection between the decline of Greece and a shortage of little fishes. There was strong reason to believe that one of the causes for the decay of “the glory that was Greece” was that malaria was brought into the State.