Roach have a bluish to silvery body colouration, while rudd will have a yellowish-brown or often even golden colour to them. Rudd have an upturned mouth, while the roach’s mouth will be downturned and the eyes of roach are red, while rudd eyes are yellowish in colour.
Carp actually have teeth, even though you cannot see them at first glance. The teeth, called pharyngeal teeth, are located deep down at the back of the carp’s throat. The fish use them to both mechanically chew and crush their food.