What is a good snail-eater in a comunity aquarium ??

The best way to rid your tank of snails is to purchase a small bottle of Freshwater Coppersafe and use it as directed. Coppersafe is, as it's name implies, a copper compound which not only is used for treatment of parasites such as common Ich, but also kills invertebrates. Since your tank has only vertebrates in it (the fish), you will not harm them. The snails however will be eliminated. I would take out the live plants for now and replace them after treatment. The snails probably were introduced into your tank with the purchase of live plants. When you purchase more, rinse them very well before planting them in your tank as you might inadvertently bring in some unwanted snails or eggs. Good luck!