fish

fish in Christian art, a fish is a symbol of Christ, and sometimes also of the newly baptized and of the Eucharist; it is often found in paintings in the catacombs. The reason for the symbolism is not wholly clear, although it may derive from the Greek letters of ‘Jesus Christ, Son of God, Saviour’ read as ikhthus ‘fish’.

A fish is an emblem of St Anthony of Padua and other saints.
The Fish or The Fishes are names given to the zodiacal sign or constellation Pisces.
all is fish that comes to the net everything can be used to advantage; saying recorded from the early 16th century. A similar thought to all is grist that comes to the mill.
a big fish in a small pond a person who is important only within the limited scope of a small field or group.
the fish always stinks from the head downwards as the freshness of a dead fish can be judged from the condition of its head, any corruption in a country or organization will be manifested first in its leaders. Recorded in English from the late 16th century. The saying ‘a fish begins to stink from the head’ is found in Greek.
fish and guests smell after three days one should not outstay one's welcome. The saying is recorded from the late 16th century, but the same idea is found in the Miles Gloriosus of the Roman comic dramatist Plautus (c.250–184 bc), ‘no host can be hospitable enough to prevent a friend who has descended on him from becoming tiresome after three days.’
fish in troubled waters take advantage of disturbance or trouble to gain one's end; recorded from the mid 16th century.
a fish out of water a person in a completely unsuitable environment or situation.
have other (or bigger) fish to fry have other (or more important) matters to attend to.
neither fish nor fowl nor good red herring of indefinite character and difficult to identify or classify; with original reference to dietary restrictions in times of fasting and abstinence.
there are as good fish in the sea as ever came out of it now often used as a consolation to rejected lovers in the form there are plenty more fish in the sea. The saying is recorded from the late 16th century.

see also better are small fish than an empty dish, big fish eat little fish, the cat would eat fish but would not wet her feet, keep your own fish-guts for your own sea-maws, kettle of fish, little fish are sweet, loaves and fishes.