Catfish Options

[CAC]

Could i get any of the following into my 38g tank, with a 4" fire eel (yes i know they grow too big for my tank, will be upgrading or selling next year..). What im thinking of are Hoplos, Upside Down Cats and Dwarf Giraffe Cats. Would there be any problems? Im not too sure about the upside downs, as theyre abit small me thinks! and would i need the hoplos to be in a group???
Any other cats for my tank?

Thanks alot, Mikey