Try this other forum posting for a key to help identify certain Polypterus: http://aquaticpredators.com/forums/i...?showtopic=643
There are several varieties of Polypterus, the Sengalus being the most redily available in pet stores since its been capitvely bread for a while, along with the albino Sengalus. The Ornatipinnis(Ornate) is also fairly available now.
Here is a list of varieties(not necessarily complete) as well as maximum sizes in the wild:
Species and sizes
maximum known sizes often smaller in captivity
P. palmas palmas ('palmas' bichir)- 13"
P. palmas polli ('marbled bichir)- 14"
P. palmas buettikoferi ('buettikoferi' bichir)- 13"
P. ornatipinnis ('ornate' bichir)- 27"
P. delhezi ('armoured' or 'delhez's' bichir)- 14"
P. endlicheri endlicheri ('saddled' or 'red' bichir)- 32", possibly more
P. endlicheri congicus ('giant' or 'congo' bichir)- 39"
P. senegalus senegalus ('Senegal' or 'Cuiver's' bichir)- 12"
P. senegalus meridionalis- 12"
P. weeksi ('week's' bichir)- 20"
P. lapradei ('Lapradei' bichir)- 24"
P. retropinnis retropinnis ('retropinnis' bichir)- 14"
P. retropinnis lowei ('Lowe's' bichir)- 12"
E. calabaricus ('Ropefish')- 15"-30"
Source here: http://aquaticpredators.com/forums/i...?showtopic=205
-- Lukasz Blaszczyk[/url]