Place: 50.098478, 14.435960 (aquarium in brmlab)
Microscope: Carl Zeiss Jenaval (Rheinberg illumination)
Description: Those are real pain among fish keepers. They live parasitic in large numbers in small intestine and rectum of fishes where they suck blood and take lot of their energy. Most of fishes dies from exhaustion. On picture are two subjects of juvenile stadium of worm in their intermediate host - crustacean of unknown genus.
More on BioOSM map