its good that ur a bichir keeper like me and alot of other people in this website. Go to the POLYPTERUS FORUM to post your bichir questions. That the scientific name for bichirs. that forum is my favourite part of MFK too. Lots of knowledgable people. now to answer ur question. a 72 gallon tank is an awesome tank to house a few (2 to 4) medium sized bichirs from 8 inches to 14 inches. The bichir species you can keep are the following......(in scienticfic names)
. Albino polypterus senegal very common
. polypterus Senegal very common
. Poypterus retropinuss rare.
. Polypterus delhezi one of my favourite rare to common
. polpterus Palmas rare to common
.Polpterus moke very rare
i live in canada too so it's accourding to my rarity sitings in Ontario.
Hope you take a look at the polypterus forum. Hope it helps.
PS: There are TONS of other larger species of bichirs to keep. Go check google and the polpterus forum for more info.
Hope it helps!