I don't think it would be a good idea, because the redtail gets quite aggressive as it grows. Plus the redtail really needs a huge tank to be cared for properly because it gets so big. I have seen one in a 200 gal. plus tank with 2 pacus, and it was getting to the point that the redtail was in need of a new home because of it's aggressiveness, eventhough the pacus were twice its size at the time.
Most folks should not have a red tail catfish because they require a very large tank, but if you can supply that, you might be able to get by with 1 or 2 in a tank with some other specially selected tankmates. Please do your research before buying one of these beauties. They are really cool, but require special care:
HI , I'm sort of new at this cause this is my first time owning my own tank,when I first got my 29 G tank I made a huge mistake by buying two oscars(one albino and one black) later I added two jack dempseys one out grew the other, one of each group is doing more than well while the black oscar and little J.D. get bullied. I'm asking what do I do since I can't afford a larger tank and I don't want any of them to die? ?????????? ???
I doubt PetSmart will take them back, but check into a local mom and pop pet/fish store and see if you can possibly trade them in for store credit, and get something else with the credit for your tank other than fish. You can also check to see if you have a local fish club and if so, you can probably find someone in the club that would be willing to buy or trade your fish.