Fish protein enzyme is a fish extract that the carp love. It has a rich, dark and extremely potent smell to it making it irresistible to a passing carp. The thick fish liquid can be used in a number of ways, including dipping hook-baits or soaking in with freebies. The main reason we at Urban use the pungent liquid, is to use it in conjunction with our fish meal base mixes at 3-5ml per egg.