Here are a few camera traps they do still shots and video easy to use - you will also need sim card and battery's - I got re-chargeable and a charger. They are great for seeing what wildlife is about especially at night when you are not about.
Looks like whatever has taken this fish has eaten some of it (hard to imagine the fish size with noting at the side of it to compare) I would go for Mink or otter.