Meet the Kombo: a multitool designed to make fileting your caught fish a whole lot easier. It has a grippy handle with a stainless steel knife and built-in sharpener inside. It also features a weighted head with 3 stainless steel weights. The below videos show Kombo in action:
As you can see, this tool floats in water. It is compact and has the tools you would need to cut through your catch. You can find out more about it here.