Boilie a boilie is a hair rig (the bait is not attached directly to the hook) which allows the boilie to sit off the back of the hook. This not only means that the bait will behave more naturally in the water (for example when disturbed by feeding fish) it also will often make the difference between a good hook hold and a bad one. Due to the nature in which a carp feeds the bait is blown out of the mouth soon after it has been picked up and the fact that the bait can move independently from the hook
Bait fish to use as bait for other fish. The terms also overlap in the sense that most bait fish are also forage fish, and most forage fish can also be used as bait fish. Baitfish can be attracted either via scent, or by using light which actually works by attracting zooplankton, a primary food source for many baitfish, which are then drawn to the light. Bait fish can also be contrasted with feeder fish. "Feeder fish" is a term used particularly in the context of fish aquariums. It refers essentially the same concept, small fish that are eaten by larger fish,