To squeeze an eel too hard is the way to lose it.
More French Proverbs:
Bread and wine start a banquet.French
He who recovers but the tail of his cow does not lose all.
French
Fine birds are commonly plucked.
French
A good man is a man of goods.
French
He who pays is fairly entitled to speak his mind.
French
The only way to keep a secret is to say nothing.
French