Most of the time I do, although i did get my apisto's without researching them too closely, the same with my dwarf gourami. That said All the fish i have are pretty good small community fish, so not a great deal of research needed. If I was going to go for something with more specific needs such as discus, a large pleco (tank size mainly), takangan (spelling?) cichlids, or any marines, then yes i would do plenty of research before making any potentially expensive mistakes.