In the FinTech world most of the developers with deep domain knowledge will know Java/C++.
Of course it really depends on what the OPs startup is trying to do.
In fact even in my city (Cincinnti, OH) there are more Java developers than any other language, but they are mostly in corporate jobs.
So here still there are less Java developers working in startups compared to other languages.
In the FinTech world most of the developers with deep domain knowledge will know Java/C++.
Of course it really depends on what the OPs startup is trying to do.