Marbled pearlfish

The marbled pearlfish ("Leptolebias marmoratus") is a species of killifish in the family Rivulidae. This threatened species is found in temporary channels within dense Atlantic rainforest, in the floodplains of rivers draining into the Baía de Guanabara, near the city of Rio de Janeiro in southeastern Brazil. It reaches up to in total length.
This species may be the only member of its genus, the inclusion of several others made "Leptolebias" paraphyletic, according to some workers. To avoid this, some authorities moved the other species to "Leptopanchax", "Mucurilebias" and "Notholebias".