I am going to assume that your were analyzing fish proteins from different fish.
Background about SDS-PAGE
Polyacrylamide gel electrophoresis (PAGE) is a simple technique for separating bio-macromolecules such as proteins and DNA on the basis of size (ie molecular weight). In your experiment, higher molecular weight proteins will move slower through the gel matrix and be found near the top of th gel while lower molecular weight proteins will migrate faster and be found closer to the bottom of the gel. The SDS component (sodium dodecylsulphate) will ensure ...
When doing a comparative analysis of proteins from similar organisms, what do similar bands on an SDS-PAGE gel indicate?