I *think* the fish mentioned are both on the allowable import lists (I may be wrong tho, someone please correct me if that is the case) so they could come into the country.. but you would need to organise quarantine at an approved facility here, which will likely be expensive.
It's doable, but is it worth it? It will be a very expensive experience.. Synodontis are readily available here (not all sp. though are common... so if yours is on the rare side it may be hard to find) and Bichirs are also available (but MUCH more expensive than over there.. looking at AUD$500+ for an endlicheri I believe...)
If it were me, I'd look into the cost to get the bichir shipped, quarantined, etc here and if it's less than $500 go for it but replace the synodontis.
That's my 2c anyway...
-Dave