I have a 20g with enough plants that I have to trim 1/3 of the plants out of the tank every 3 or 4 weeks. There is also a big population of ramshorn and pond snails, 2 large Black Mystery snails, and 1 lone Betta. My wife loves the snails and insists that they be fed. To maintain the snail population do they need to be fed? If so, what should the snails be fed?