Only with big bichirs like ornates and the endlii's. And the bichirs petsmart sells are albino senegalus and don't get over 11", they're actually the more peaceful of the bichir species and are a good beginner bichir. I personally have a delhezi and he's awesome. But the Oscar should be ok with only the bigger of the bichirs, like the ornates and the endlicherii endlicherii bichir. You may see a squabble over foods but I doubt anything serious will happen. And other people may disagree with me but adult bichirs generally need to be kept solo, like not alone in their own tanks like fahaka puffers but just no more bichirs in the tank. Bichirs get along with other bichirs fairly well when young but I've found that they don't do so hot together when older so I only recommend getting one.