If you cannot find a specific antibody that detects zebrafish insulin, try a polyclonal antibody, such as guinea pig.anti-human insulin antibody.

Since insulin sequence is well-conserved, it is much more likely that a polyclonal anti-insulin serum (or IgG) will have a fraction of IgG molecules which recognize shared epitopes between the two species.

many thanks 

Go through this paper

\Analysis of beta cell proliferation dynamics in zebrafish

Developmental Biology

Volume 332, Issue 2

thanks