^ This. Just don't squish by hand. :rofl:Pull them out and squish them.
Don't worry about whether to add a fish or not to take care of them. You won't find one that'll live in that size tank. Even a lot of puffers have trouble with Trumpet Snails. They are some of the toughest snails to crack.
Take a bunch out, put them in a container, smashy smashy....fish food.
Also, snail population explosions arn't always from overfeeding. It is often the most common reason and so the first thing to try to fix, but they are scavengers so it isn't the only reason. Excess algae growth as well as rapid plant growth (it isn't the plant growth itself but the unnoticed die-off that can come with it) can also cause a population boom.