When Europeans (French) discovered the genus Polypterus in 1809 it had already been known along the Nile since the time of the pharoahs. The local peoples referred to them as bichirs (unknown pronunciation and spelling). While unable to come up with an exact meaning for the word it was most likely a descriptive term (''whip'' has been suggested) for this type of fish.
The French most likely pronounced it as phonetically as possible to the orginal native word and came up with bee-sheer as a pronunciation and spelled 'bichir'. Since this would be the name of these fish for
several years until they were scientifically described and put into the proper family it became an accepted common name.
However the correct English pronunciation is up for grabs. Several dictionaries all have their own pronunciation including the below:
bir chir is common in England
Also known by the common name lobed fin pike,dinosaur eel.
The name Polypterus : poly=many + pterus=fins and is pronounced po-lyp'-terus.
arguing every detail of how to pronounce latin names is asinine in the end; the scientific community even pronounces various scientific names differently...in most cases they have moved well past arguing about that and on to (at least theoretically) more worthwhile arguments and issues.
and for the record, most ichthyologists and fish ecologists i know pronounce that second "p", and when it shows up similarly in invertebrates, most entomologists and the like also pronounce it.
so, one can sound different and say it how they think is correct in the case of Latin names, but i would be slower to criticize telling other people they are wrong. won't help one's case or make many friends --