Block. Seafood that has been placed in a form or carton and frozen in a plate freezer. Block-frozen products include shrimp, scallops, crab meat and finfish, including pollock, cod, haddock, flounder and whiting. Fish blocks, usually without skin and bone, are used as raw material for fish sticks, portions and as breaded or battered items. Shown is a 15-pound block of Alaska pollock. 

Cellopack. The most common pack for frozen groundfish fillets, which are wrapped together, one to three fillets per ungraded packet, in cello phane or polyethylene film. Shown is a 5-pound cellopack containing six packets of Pacific cod. Since they are ungraded, cellopacks are comparatively inexpensive. They can also utilize irregular cuts not appropriate for other packs. 

Layerpack. Packs in which high-quality, carefully graded fillets are layered with edges slightly overlapping so they freeze together. The layers, typically no more than four, are separated by polyethylene sheets, allowing fish to be divided and removed (usually an entire layer at a time) while still frozen. Shown is a cross section of a 15-pound Pacific cod layerpack. 

Shatterpack. Essentially, layerpacks that can be dropped or struck against a hard surface to break apart frozen fillets. Shatterpacked fish is wrapped in a manner that prevents the fillets from sticking together, allowing more control over the number of fillets removed at any one time. Shown is a cross-section cut from a 15-pound shatterpack of Alaska pollock. 

IQF. Individually quick-frozen, glazed fillets (or shellfish like shrimp and scallops) packed loosely in a polyethylene-lined box. These size-graded products retain their natural shape and are very easy for the end user to handle. However, the boxes occupy more storage space than other packs and are more easily damaged. Shown is a 25-pound box of 4- to 6-ounce IQF Alaska pollock fillets.