Just looked up Polypterus Diet These are results from Lake Chad
Polypterus endlicheri as observed include Tilapia species (89.3%), Eutropius niloticus(Type of Catfish) (28.6%), Mayfly nymph (39.3%), Dragon fly larva (56.6%) fish remains (21.4%) and detritus (7.1%).
Polypterus senegalus as observed include Tilapia sp (88.4%), Eutropius niloticus (27.9%), may fly nymph (23.3%), Dragonfly nymph (34.9%) remains(21.1%) detritus (23.3%).
Remains and Detritus are Fish
http://aquacomm.fcla.edu/1265/1/FISON2003_186-193.pdf
According to the paper the feeding of all polys seems to be the same
