skipjack: medium-sized tuna-like food fish of warm Atlantic and Pacific waters; less valued than tuna
bonito: any of various scombroid fishes intermediate in size and characteristics between mackerels and tunas
acquired immunity: immunity to a particular disease that is not innate but has been acquired during life; immunity can be acquired by the development of antibodies after an attack of an infectious disease or by a pregnant mother passing antibodies through the placenta to a fetus or by vaccination