with snails you just have to see which ones are smart and which ones are stupid! I originally bought 12 large turbos for my tank with a large golden puffer and a clown trigger. THere are still 8 left, they dont come out at all during the day, but are very busy at night. The other 4 would fall over all the time and didnt learn to not be active when the light are on. I also have cowries. Have had no problems with them, the tend to stay in their shell more, but again they dont come out until the light are off.