I've swapped out a whole tank full of fish just because I changed my mind! I started with rosy barbs and rainbowfish and decided I wanted to go with cichlids so I scooped everybody up and brought 'em back to the lfs for credit on new fishies!New Boy said:OK, so everyone seems to agree on aggressive fish etc, how about if you obtain some fish when you first get in to fishkeeping and really didn't research at the time, you then research as you get more in to the hobby (and don't rely on lfs staff as much - some give good advice but for every good one there's probably two bad in my experience) and discover that the fish are not going to be ok in your tank for the long term - do you exchange then? Or look after them as much as poss until the point you have to change....
They don't have a problem with it (of course not, they give me 50% back of what I paid them in the first place ) so why should I?