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Abstract

The bullhead has four pairs of barbels: the medial nasal barbels and the lateral maxillary barbels located in the upper jaw area, and the lateral and medial mandibular barbels located in the lower jaw area (Fig. la). In the resting position the barbels characteristically spread out in this fish. From a frontal view when the ends of the bullhead barbels are joined, the result is a trapezoid-shaped outline (Fig. la), the so-called Fronttrapez (Schiche, 1920). Even though the barbels occur in different positions, they show much the same structure, so no special information about the origin of the barbels will be given. The barbels differ only in length, the maxillary barbels being the longest, and in pigmentation, the nasal barbels being darker than the mandibular barbels and the maxillary barbels appearing darker on their upper side than on their bottom side. The barbels have an egg-shaped transversal section, the obtuse rounding representing the barbel surface pointing to the front.