Variability of plastic features of size groups of the american catfish <i>Ameiurus nebulosus</i> (Lesueur, 1819) – alien species in the water bodies of Belarus

A scheme for measuring the plastic features of brown bullhead, including 28 morphometric characteristics, has been proposed. Based on cluster analysis size groups species a model water body were determined (Karpin village pond, Maloritsky district, Brest region). The change in exterior parameters bullhead during its ontogenesis shown first time. It is proposed to divide individuals into 3 analysis: – young not involved reproduction (body length without caudal fin up 135.0 mm); B mature that have started breeding (sizes from 136.0 174.0 C adults, actively 175.0 187.0 mm).