A dictionary of Proverbs (Oxford Paperback Reference)

The FISH always stinks from the head downwards
The freshness of a dead fish can be judged from the condition of its head. Thus, when the responsible part (as the leaders of a country, etc.) is rotten, the rest will soon follow. Gr. 'a¹ f' - a _•; t?/.,'/ j i t?a /'■•:г«?.■. a fish begins to stink from the head.

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  1581 G. PETTIE tr. S. Guazzos Civil Conversation III. 51 If the prouerbe be true,.. that a fishe beginneth first to smell at the head,.. the faultes of our seruantes will be layed vppon vs. 1611 R. COTGRAVE Dict. French & English s.v. Teste, Fish euer begins to taint at the head; the first thing that’s deprau’d in man’s his wit. 1915 W. S. CHURCHILL Letter 3 Dec. in M. Gilbert Winston S. Churchill (1972) III. Compan. II. 1309 The guilt of criminality attaches to those responsible. ‘Well,’ said the Aga Khan, ‘fish goes rotten by the head.’ 1981 Sunday Telegraph 3 May 16 ‘The fish’, as the saying goes, ‘always stinks from the head downwards.’ Last Sunday we deplored Mr. Michael Foot’s liking for the street politics of marches and ‘demos’. Since then, a hundred Labour MPs.. have followed their leader’s example. 2002 Washington Post 19 Mar. A21 Cardinal Law has to go. The Vatican has to speak up. This fish, as they say, rots from the head. ■ rulers and ruled
  

FISH and guests smell after three days
Cf. PLAUTUS Miles Gloriosus 1. 741 nam hospes nullus tam in amici hospitium devorti potest, quin, ubi triduom continuom fuerit, iam odiosus siet, no host can be hospitable enough to prevent a friend who has descended on him from becoming tiresome after three days.

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  1580 LYLY Euphues & his England II. 81 As we say in Athens, fishe and gestes in three dayes are stale. 1648 HERRICK Hesperides 169 Two dayes y’ave larded here; a third yee know, Makes guests and fish smell strong; pray go. 1736 B. FRANKLIN Poor Richard’s Almanack (Jan.) Fish and visitors smell in three days. 1869 Notes & Queries 4th Ser. IV. 272 ‘See that you wear not out your welcome.’ This is an elegant rendering of the vulgar saying that ‘Fish and company stink in three days’. 1985 J. S. BORTHWICK Down East Murders iv. How long should she stay? She remembered the universal truth that fish and guests smell after three days. 2001 Washington Times 21 Nov. B1 Fish and visitors smell after three days, the old adage goes. Yet the experience of hosting a crowd for an extended time over the holidays need not leave a bad taste—or odor—for someone prepared to cope. "hospitality