Petrocephalus longianalis is a species of electric fish in the family Mormyridae. It is found in the lower and upper Luapula River system in Zambia.
This species reaches a length of .
The fish's name means longus (L.), "long"; analis (L.), "anal", referring to higher number of anal-fin rays (30âÂÂ35) compared with congeners covered in the authors' study.