A drain plug for installation into the in-floor fish-boxes on fishing boats. It is a removable and reusable filter that prevents detritus and other unwanted items from entering the fish-box drain system. The filter is a raised screen filter that allows water to drain out of the In-floor fish-box while preventing undesirable material from draining. Once the in-floor fish-box has been drained, the drain plug is removed for cleaning, and then reinstalled after cleaning.