This tripod type rod stand has a hook under it to hang a small bucket on. The bucket can be used for bait, or actual fish caught. An aerator can also be attached to the bucket to keep bait or live fish in good condition. With just clean water in it, can be a convenient way to wash hands after handling bait. In very strong wind, the extra weight of the water can help keep the stand from blowing over.
In this case, the bucket is a soft collapsible type, with a flatfish and a couple of other fish inside, all were released.