Uhm, did you cycle your tank yet? And do you do water changes/gravel vacs at least once a week, or daily if the tank is cycling? Unless you're serious about getting a large enough tank for them 55-75 gallons within a few weeks or so I'd rehome them and instead get some dwarf corydoras, neon tetras, or other small fish that isn't too active. And please disregard anything that the lfs people say, they may be nice but they're really just sales people and for the most part don't know much about fish, or just want you to buy a fish and get out of there. Also, your lfs may make you bring in a sample of your water when returning a fish, and if the tank is cycling then you won't get a refund.