[1] Aristophanes, Clouds 339; Doric genitive plural of κέστρα . The word κέστρα is also glossed in Hesychius: "defensive weapon, hammer. And a kind of fish". Photius glosses it as μύραινα , "murry". The phrase is also cited (in Attic) in tau 295.
[2] Definition taken from the scholia vetera. The scholiast attempts a distinction between κέστρα [~ κεστρέα ] and κεστρεύς . On κεστρέα , see kappa 1430.
Both fish names derive from the literal meaning of κέστρα , "hammer". In LSJ, κέστρα is a σφύραινα (also a "hammer" fish, as identified by Athenaeus, Deipnosphists 7.323A-C [7.122 Kaibel]), and a σφύραινα is either a "bicuda" ("Sphyraena spet") -- or a κέστρα . Dalby 2003 s.v. barracuda identifies the κέστρα and the σφύραινα with the Sphyraena Sphyraena, the European barracuda, called spet in French.
The κεστρεύς on the other hand is defined in LSJ as a mullet, and the κέφαλος a kind of mullet. So LSJ does not commit to the identity of the κέστρα and the κεστρεύς . On the κεστρεύς see also kappa 1432. On the identification with the κέφαλος , see kappa 1431.
[3] This gloss appears unique to the Suda.
[4] Mangling of a prescription in Phrynichus 12: "One will not correctly say τέμαχος "slice" of meat, cake, or bread, but τόμος ; τέμαχος is said only of fish." By the time the phrase ends up in the scholia vetera on Aristophanes, Clouds 339b, it is rearranged: "τέμαχος is said of fish and cake; never of meat". Though the Suda takes up the scholiast's prescription, "meat" is here substituted with "wheat", and in tau 295 with "peas".
[5] The "fasting mullet" (νῆστις κεστρεύς ), a commonplace of Comedy (kappa 1432), is expanded out to the sentence given, "the mullet fasts", in Athenaeus, Deipnosophists 7.307C [7.79 Kaibel], Plutarch, Proverbs used by the Alexandrians 1.8, Pausanias, Ἀττικῶν ὀνομάτων συναγωγή κ .29, Libanius, Letters 332.2, Patriarch Gregory II, Proverbs 2.90, Apostolius 9.76. In LSJ s.v. κεστρεύς , it is glossed as "of those too honest to make gains". The proverb is interpreted differently in Diogenian 5.53 (Mazarin codex): "concerning the greedy, who pretend to fast; for the animal is insatiable" (on the gluttony of mullets, discussed in Aristotle, see kappa 1432).
The two interpretations are merged together in Diogenian 3.1 (Vienna codex) and Zenobius 4.52; in Diogenian's wording: "concerning the very greedy. [Zenobius adds: For the mullet is so insatiable, that as a results those who gape and drink were called mullets, being greedy.] But it is also said concerning those who act honestly, but walk away with nothing more than justice. For while other fish eat each other, the mullet alone abstains from eating flesh, and feeds on mud". The Suda's wording combines Pausanias for the first sentence, and Diogenian for the second. The proverbial saying is also glossed in Photius s.v. κεστρεῖς , whose wording overlaps with the Suda.
[6] Namely "not carnivorous", as Diogenian, Zenobius, and Athenaeus already indicate; see kappa 1432.