Loads of loaches would suit those basic criteria, which are cyprinids and not catfish by the way, making corydoras loaches impossible under normal circumstances
Is this tank empty of fish and wanted critters, or are their existing inhabitants that the loaches need to be compatable with?
Botia species will come out in the open if they have plenty of hiding places and pals around. Or if you get Botia Histrionica all the time no matter what, these aren't shy loaches.
Night61, what loaches do you refer to? A single Botia Striata demolished a snail infestation in my tank in two days!