My gold mystery snail demolishes plants. He ate all the leaves from a radican sword in two days, then moved on to my Red Ludwigia. He leaves the anachris alone for the most part, but he really loves broad leaves. I've heard that some people supplement their snails' diet with lettuce to help curb their appetite for plants, but I have not tried that yet. Guppies tend to nibble algae and soft, dead leaf matter from plants, but they dont eat the plants themselves. They do tend to get a little frisky when the lights go down and uproot a lot of the plants though. I thought, at first, that my guppies were devouring my plants, but it turns out that their energetic swimming was merely uprooting the shallow plants and knocking all the leaves off of them. Bettas leave my plants alone all together and the Neon Tetras didnt bother them either. My shrimp hang out in or on my plants to find food, but they dont eat the plants themselves.
A lot of people have good luck keeping plant eaters in planted tanks if the tank is large and heavily planted. Under the proper conditions, plants will grow rapidly and losing them as food doesnt become as big a problem as it does when you have smaller tanks or fewer plants available. In all, I've found that its best to have a deeper substrate (2-4 inches) for planted tanks...this helps keep them in place, as a lot of fish are quite frisky swimmers and will uproot shallow plants easily. I haven't tried keeping a planted tank with a lot of different fish, so I don't know how plants will survive certain species. I also keep a seperate grow out tank with sand substrate just to grow plants in. Quite often, I have to remove a plant from the main tank that is missing most of its leaves and replant it in the grow out tank to let it grow. With more of a mature plant selection I may not have to do this, but I'm not the type to buy a tankfull of plants in one shot. I usually just get one or two that I like and try to grow them in the spare tank to increase my population. I'll put a single stem or two in the grow out tank and the rest in the main planted tank. It doesnt take long before I have twice as many as I started with.
