Passage 9.24.2
λέγουσι δὲ οἱ Βοιωτοὶ καὶ πολίσματα ἄλλα πρὸς τῇ λίμνῃ ποτὲ Ἀθήνας καὶ Ἐλευσῖνα οἰκεῖσθαι, καὶ ὡς ὥρᾳ χειμῶνος ἐπικλύσασα ἠφάνισεν αὐτὰ ἡ λίμνη. οἱ μὲν δὴ ἰχθῦς οἱ ἐν τῇ Κηφισίδι οὐδέν τι διάφορον ἐς ἄλλους ἰχθῦς τοὺς λιμναίους ἔχουσιν· αἱ δὲ ἐγχέλεις αὐτόθι καὶ μεγέθει μέγισται καὶ ἐσθίειν εἰσὶν ἥδισται.
The Boeotians say that other towns, once inhabited, called Athenae and Eleusis, existed near the lake, but one winter season the lake flooded and caused their disappearance. The fish inhabiting Lake Cephisus do not differ at all from other lake-fish, but the eels found there are the largest in size and most delicious to taste.