Eat it: Canned (it's cheaper than fresh).
Sardines: Don't overlook these tiny canned fish. They're less expensive than fresh fish (think cod and tilapia), yet still high in protein (one can contains about half your daily requirement). Plus, they're packed with omega-3 essential fatty acids which, along with protein, can aid weight loss.
Eat them: On top of whole-grain crackers or tossed in a salad.