Contribution to the knowledge of ichthyofauna of the Mlava River (a tributary of the Danube) with an emphasis to the spawning pattern distribution of brown trout (Salmo trutta fario L., 1758)

Abstract

The fish fauna distribution of the Mlava River upper course denotes it as salmonid, with a gradual transition to the barbel region at the lowest profile. Only one (the rainbow trout) of 8 lamprey and fish species is allochthonous. The lamprey species found, the Vladykov's lamprey, is reported for the first time in the Danubian watershed of Serbia. Saprobiological evaluation on the fish fauna composition denotes the upper course of the Mlava River as xenosaprobic, and indicates the main pollution sources on it, but definite and precise saprobic evaluation is to be complemented by other investigating approaches on that item. The distribution pattern of the brown trout Salmo trutta fario in the upper course of the Mlava River (three investigated profiles), its size-classes (below and over 0.25 m) distribution and gonadal condition in both sexes clearly revealed the foregoing spawning.