Secondary antibodies should be raised based upon the primary antibody you are using that produced by different host species. If your primary antibody is a mouse monoclonal, the secondary antibody should be an anti-mouse Ab. Similarly, a rabbit monoclonal primary antibody will correspond to an anti-rabbit secondary Ab. In addition, secondary antibodies conjugated to fluorochromes and chromogens depend on your project requirements.https://www.antibody-creativebiolabs.com/technical-faqs.htm