Straminipilous Organisms Growing on Herbivorous Pirapitinga (Piaractus Brachypomus) and Carnivorous Piranha (Pygocentrus Nattereri) from Poland/Organismos Stramenophila Em Crescimento Na Herbivora Pirapitinga (Piaractus Brachypomus) E Na Carnivora Piranha (Pygocentrus Nattereri) Da Polonia (Report‪)‬

1. Introduction In their natural environment, Piaractus brachypomus and Pygocentrus nettereri inhabit inland waters of South America (Thorson, 1976; Menni et al., 1996). In many countries, including Poland, both species are reared in amateur aquaria for their characteristic body colouration and original appearance. In aquarium conditions, they sometimes alter their behaviour, e.g. predatory piranha lose their aggressive disposition, become anxious and skittish, retaining, however, their atractive look due to their colourful skin. The aim of this study was to supply some data to extend the list of straminipilous organisms growing on chosen parts of the body of the pirapitinga and piranha specimens, used as baits. The result was to compare the composition, abundance and diversity in water from three trophically different water bodies in Poland.