A multi-coloured fishing line serves several practical purposes for anglers. The different colours help in monitoring the line’s movement and depth, especially in varying water conditions. This visual aid allows you to track the line's position and detect any changes or slack more easily. Multi-coloured lines can also be helpful in setting specific depths or keeping track of the distance between the lure and the boat. They also enhance visibility for the angler, which can be beneficial during night fishing or in murky waters.