Matsya Purana — Characteristics of Dvāpara and Kali Yugas
ते ऽपि मत्स्यान्हरन्तीह आहारार्थं च सर्वशः अभक्ष्याहारदोषेण एकवर्णगताः प्रजाः //
te 'pi matsyānharantīha āhārārthaṃ ca sarvaśaḥ abhakṣyāhāradoṣeṇa ekavarṇagatāḥ prajāḥ //
They too, everywhere in this world, seize fish merely for the sake of food; and through the fault of eating what is forbidden, the people fall into a single, undifferentiated social condition, losing the proper distinctions of varṇa.
It does not describe cosmic pralaya directly; it highlights moral and social dissolution—how adharma, especially food-transgression (abhakṣya-āhāra), becomes a sign of the age’s decline.
It implies that householders must follow rules of permissible food (bhakṣya/abhakṣya) to maintain personal purity, and that kings should uphold dharma by discouraging widespread dietary misconduct that leads to social confusion and loss of orderly conduct.
No Vāstu or temple-architecture rule is stated; the ritual takeaway is āhāra-śuddhi—purity of diet as a foundational discipline supporting dharma and social stability.