Passage 8.21.2
εἰσὶ δὲ ἰχθῦς ἐν τῷ Ἀροανίῳ καὶ ἄλλοι καὶ οἱ ποικιλίαι καλούμενοι· τούτους λέγουσι τοὺς ποικιλίας φθέγγεσθαι κίχλῃ τῇ ὄρνιθι ἐοικός. ἐγὼ δὲ ἀγρευθέντας μὲν εἶδον, φθεγγομένων δὲ ἤκουσα οὐδὲν καταμείνας πρὸς τῷ ποταμῷ καὶ ἐς ἡλίου δυσμάς, ὅτε δὴ φθέγγεσθαι μάλιστα ἐλέγοντο οἱ ἰχθῦς.
In the Aroanius river there are fishes, both of other kinds and those called "poikiliai" (“spotted fish”); these “poikiliai” fish are said to produce a sound similar to that of a thrush. I myself saw them after they had been caught, but though I remained by the river until sunset, the time when they were said particularly to emit their voices, I heard nothing.