My boyfriend has a 10 gallon with four priscilla tetras, one tiny zebra daino, one oto, some plants... and now 10 million snails!!! We don't know what happened, but he had three snails originally. Apparently they have been mating like rabbits (they sit there and suction on eachother a lot, so I don't know if that's when they're mating?) And in the past two weeks, when the light is off, we see literally hundreds of baby snails. One on almost every single one gravel piece on the bottom. We thought maybe not all of them were going to survive, but they are all getting bigger. I have never seen this before! I have snails in my own 20 gallon, and once in a while I'll notice a new one, but not a ton at once like this! Can anyone tell me why this is happening? Does he just happen to have very ideal conditions for snails to mate? Will the snails harm the fish in any way? I think the snails are very freaky because now there are so many. The larger original three are also SUPER active and are almost completely out of their shell when they "walk" around the tank and glass. They also float upside down and suction the water surface too. What's going on?? 
