pisk-

Root yielding Latin piscis, English fish, Pisces, piscine.‌​‌​‍​‍​‌​‌​‌​‍​‍​‌​‌​‍​‍​‍​‍​‌​‌​‍​‍​‌​‍​‌​‌​‌​‌​‌​‍​‍​‌​‍​‌​‍

Discussion

The PIE noun *pisk- (fish, aquatic creature) produced the word for fish in the western branches of t‌​‌​‍​‍​‌​‌​‌​‍​‍​‌​‌​‍​‍​‍​‍​‌​‌​‍​‍​‌​‍​‌​‌​‌​‌​‌​‍​‍​‌​‍​‌​‍he IE family, though its PIE status has been debated: some scholars consider it a western IE innovation rather than a common PIE term, since the eastern branches use a different word (*dʰǵʰuH-, giving Sanskrit jhasá-).

Latin piscis (fish) is the central reflex and the source of the English zodiacal term Pisces (the Fishes), piscine (pertaining to fish), pisciculture (fish farming), and the ecclesiastical symbol of the fish (the early Christian ichthys, though that word is Greek, not from this root). The Romance languages continue Latin piscis directly: Italian pesce, French poisson, Spanish pez/pescado, Portuguese peixe.

Old English fisc (fish) descends from PGmc *fiskaz, from PIE *pisk- with regular Grimm's Law: PIE *p > PGmc *f. Modern English fish, German Fisch, Dutch vis, and the Scandinavian forms all continue the same word. The regularity of the correspondence — Latin pisc-, Germanic fisk- — is a textbook demonstration of the *p/*f alternation predicted by Grimm's Law.

Old Irish íasc (fish) provides the Celtic reflex (with regular Celtic loss of initial *p-). This Celtic loss of *p is one of the defining features of the Celtic branch and explains why Irish has no initial p- in inherited vocabulary.

The word's absence from Indo-Iranian and Greek (which uses ikhthýs, from a different root) has led to debate about whether *pisk- was a true PIE word or a late western innovation. If it was PIE, the eastern branches replaced it; if it was western IE, it spread across Italic, Celtic, and Germanic before those branches fully separated. Either way, the word's consistent form across the western branches confirms its antiquity within that group.

The cultural significance is clear: PIE speakers caught and ate fish. The reconstruction of *pisk- alongside terms for fishing nets and hooks (less securely reconstructed) points to a riverine component of the PIE economy complementing the better-attested pastoral activities.