I have been Keeping btas and mini carpets for years, never lost a fish yet. If an anemone dies in your tank it is the amonia spike that could cause a problem in your tank. Larger species of carpet anemones are known for eating fish, and some crabs, snails just about anything that wanders it's way. Any anemone has the ability to eat a fish, I believe your risk is minimal with either bta or lta. Is your tank large enough so your fish can easily swim freely and avoid it. You can use moonlites as well so they don't stumble into it in the darkness. Don't rely on what your told, many LFS sales people are uninformed. Try google or wetwebmedia search on the species your interested in, loads of reliable information out there.