If you have other fish to fry or have bigger fish to fry, you have something more important, interesting, or profitable to do. I didn't pursue it in detail because I'm afraid I had other fish to fry at the time. She tried to avoid wasting time on bureaucratic squabbling. She had bigger fish to fry. Note: This phrase is often varied. For example, if someone has their own fish to fry, they are not interested in doing something because they have business of their own to deal with. Tony comes and goes. He's got his own fish to fry, as they say.