chained_bear commented on the word mackerel-snapper I get the fish-eater thing, but I don't know why non-Catholics wouldn't want mackerel--evidenced by the use of the term in a disparaging phrase. (Or wouldn't want snapper, for that matter.)
Psalm 1 is the first of the Psalms in the Hebrew Bible. Like many of the psalms, it contrasts the  righteous  person (tzadik ×¦×××§) to the wicked or ungodly (rasha` ×¨×©×¢) or the  sinner  (chatta' ×××).
The psalm was recited by one chanter, to whom the people answered with a refrain or response, the latter being either the alternate verses of the psalm itself, or one verse repeated again and again, or sometimes a sentence taken from elsewhere.