Piscicola geometra - The common fish <a href="//commons.wikimedia.org/w/index.php?title=Leech&amp;action=edit&amp;redlink=1" class="new" title="Leech (page does not exist)">leech</a>, <i>Piscicola geometra</i>, a <a href="//commons.wikimedia.org/wiki/Parasite" class="mw-redirect" title="Parasite">parasite</a> of freshwater fish such as salmonids, pike, perch, and bream. © Mateusz Bocheński - CC BY-SA 3.0 - Wikimedia Commons