A monster fish has washed up at a beach in Bundaberg weighing over 150 kilos and measuring nearly two meters in length.

The couple who found the fish posted a photo on social media to try and help identify the species, but when they returned the next day the fish had gone.

A spokesperson for Queensland Boating and Fisheries Patrol says if anyone suspects illegal fishing activity has been going on to report it to Fishwatch on their 24-hour toll-free hotline on 1800 017 116.