Meaning
Lit. “healthy as a fish” – which means to be in a perfect condition, healthy and strong, with no complaints whatsoever. The expression is used following medical check-ups but also as a response to someone asking about a person who has recently been sick.
The Poles who have long time ago coined this phrase must have thought that fish generally rarely become ill, maybe because they spend all their life in cold water and feel great there. Or maybe because fish is generally considered a healthy food. The “healthy as a horse” – “zdrów jak koń” also functions in Polish language, however, it is less popular than the “zdrów jak ryba”.
The “zdrów” is a somewhat obsolete but also shorter form of the adjective “zdrowy/zdrowa”, which only covers the male grammatical gender. A female counterpart does not exist – you use the modern form “zdrowa”.
Example:
Chcesz być zdrów jak ryba, jedz owoce i warzywa.
Mężczyzna, który wcześniej był zdrów jak ryba, i który z sukcesami leczył swoich schorowanych pacjentów, zaczął słabnąć.
Loki to niemal 14 letni labrador, który przez większość swojego życia był zdrów jak ryba.