We bought some baitfish at the tackle shop for tomorrow's bass fishing trip.

baitfish 是由 bait（鱼饵）和 fish（鱼）组成的复合名词，字面意思是"用作鱼饵的鱼"，指那些体型较小、常被用作活饵或死饵来吸引大型鱼类的小鱼。