Do they ever swim or float or do they just walk?
They float around all the time. That second photo is Bruno in the very act of parasnailing - he climbs up to the plants at the top of the tank, scoots off, and floats down to the bottom. It's quite a common thing for snails. If you have a bubble wand or airstone in the tank, they will play in the bubbles, spreading out their foot and trapping air underneath so they can hover. It's really charming.
Awesome goldfish and snails!! The goldfish never bother them? I would love to get some for my tank but I didnt think they could be in my unheated goldfish tank...
Do they have a specific name that I should look out for? How big do they get? Sorry I'm a snail noob! hahaha
The goldfish mouth and bump them once in a while when I feed the snails algae wafers or other treats, because they are such piggies. But other than that, the occasional mouthing, they never bother them.
My goldfish tank is always quite warm, but the snails are comfortable at about 70 and above.
Pomacea bridgesii are the "mystery" snails you'll find at most LFS. They grow to about the size of a golf ball, and they'll eat dead plant matter, slightly cooked veggies, algae wafers, sinking fish food... just about anything.
In the shot with the blue background, the two largest snails are Pomacea Haustrum. They grow much larger, to about the size of a tennis ball, but they're harder to find in the aquarium trade and they're sort of a gray area as far as shipping, since they're voracious plant eaters. Some species of Pomacea have shipping restrictions because they're considered pest snails. But they're all legal to own, so if you can find them within your state, you're fine. Snails are great. I love mine.