Aegagoropile linnaei, aka Marimo is not a carnivorous plant, but a unique type of algae that grows spherically, and is endemic to Japan, Iceland, Estonia, Scottland, and Australia.  This cultured Marimo is about 1cm in diameter.  It would be a great addition to your fish tank with no algae eating fish or animals like shimp, snails or crabs.  It can also be a fantastic addition to a miniature stand alone aquarium.  Keeping Marimo is easy.  Just change water monthly with regular tap water and keep it on a windowsill with moderate light or under a desk lamp.  A perfect companion in a small apartment.