Companies are often providing specific antibody pairs for capture and detection antibody, however, when this is not the case one can test the following approach:

Capture antibody can be either from the same species as detection antibody, for example: rabbit 


Capture antibody and detection antibodies are from different species, for example, rabbit and goat. 

Both approaches are going to work, however, using a different host of capture antibody might offer better selectivity, while using with the same host of capture Ab as detection antibody may offer less background/noise. Therefore, it may be worth to explore both options, as the outcome will depend upon sample type and requires assay sensitivity. 
Which antibody to use as a capture antibody?

Agrisera offers thousands of unlabeled and labelled secondary antibodies to a wide range of hosts. Explore our collection here.