Weaving, finger painting, printing, colouring in, cutting and gluing are all ways to develop your child’s fine motor skills.
Why not use the Christmas cards you are going to discard to make the scales for your own Rainbow Fish.
Use a cereal box to cut out a fish shape cut slots in the card where you could use leftover wrapping paper to weave in between to create your fish.
Using clothes pegs to hold cotton wool or if mums and dads have any bottle corks use these to print the scales on your fish shape.
Or using whatever you can find around the house make a mosaic fish by cutting small bits of car/paper using these to create the scales.