The objectives of this work were to develop hematological methodologies for fish, determine effects of stocking density on fish hematology, define, characterize, quantify baseline hematological values of adult bluegill, and provide a selected and annotated bibliography of baseline and temperature studies on fish blood. A survey of the literature indicated that more studies are needed to determine normal (nonstressed) blood parameter values for freshwater teleosts. Standard clinical methods, with some modifications for small blood samples, are adequate for fish hematological studies. A density stress syndrome seems to exist for goldfish, catfish, and bluegill. Blood dyscrasias associated with density stress include smaller and rounder red blood cells, hyperglycemis, an increase in albumin/protein ratios, and decreased values for hematocrit and hemoglobin.