鯛の尾よりも鰯の頭 [たいのおよりもいわしのかしら] – It’s better to be the head of a sardine than the tail of a sea bream.
This saying is akin to something like “Better to be the head of a dog than the tail of a lion” in English. While I don’t agree with the “don’t be too ambitious” slant of the saying at all, it’s still pretty cool. Plus, there are the names of two fish in there, so hey… free vocab!
Note also that 頭, which is often pronounced あたま is, in this case, read かしら.