Lightly salted sturgeon eggs (roe). Because fresh caviar is highly perishable and requires special handling, it is very expensive. Eggs or other fish are used to make less costly caviar substitutes, but the label must list the type of fish. You're likely to find whitefish, lumpfish, salmon (red caviar), tuna, cod and carp caviar. Look for caviar in small jars in supermarkets and specially stores. One tablespoon of caviar has about 40 calories.