Scubagolf
Contributor
"A few fish can actually swim upside down for long periods one of these is the upside-down catfish, originally from the Congo and now kept in freshwater aquariums around the world."
Reference: www.sealifeeurope.com/sealifeeducation/_pdf/pupil/movement_pupil.pdf
Reference: www.sealifeeurope.com/sealifeeducation/_pdf/pupil/movement_pupil.pdf