Blind a shoaling fish such as a herring and it can still follow its mates. Cut its lateral lines and it rapidly gets lost.

群体性鱼，比如鲱鱼的眼睛被弄瞎后，它仍然能跟随同伴前进，而除去侧线的鲱鱼则会很快迷失方向。

youdao

If you don't, this will be like trying to cut down a redwood tree with a herring (your skills being the herring).

如果您不知道怎样做，那么这就像是企图用鲱鱼来砍倒红杉树(而您的技能就是那条鲱鱼)。

youdao

But Conservative Party chairman Grant Shapps told the same programme the top rate tax cut was a "red herring" and pointed to the removal of millions of people on lower pay from income tax.

BBC: Battle over plan to cap benefits ahead of Commons vote