Every person who files as a candidate for county sheriff must be licensed as a peace officer in this state. Every person appointed to the office of sheriff must become licensed as a peace officer before entering upon the duties of the office. Before entering upon duties every sheriff shall give bond to the state in a sum not less than $25,000 in counties whose population exceeds 150,000, and not less than $5,000 in all other counties, to be approved by the county board, conditioned that the sheriff will well and faithfully in all things perform and execute the duties of office, without fraud, deceit, or oppression, which bond, with an oath of office, shall be recorded with the county recorder.