Have bigger/other fish to fry
Definition 1 of 1
Pro Tip 1/3Prioritizing Tasks
It suggests ranking tasks by importance and urgency, focusing on the most critical ones first. 
The boss said to skip the meeting – we've got bigger fish to fry with the project deadline looming.
Pro Tip 2/3Casual Tone
Used in informal situations, not usually in formal writing or speeches unless adding a human touch. 
No time to chat now, I've got other fish to fry!
Pro Tip 3/3Metaphorical Use
It's a metaphor; there's rarely actual fish involved. It speaks to tasks or issues metaphorically. 
Can't join the game tonight, I have bigger fish to fry with my studies.