What snails are these?

I just got a cup of duckweed, and found these little guys in the cup. Any idea what kinds of snail they are? One is dark and had a pointy shell, and the other is a little light and has a round shell. Both smaller than my pinkie nail. Can/should I put them in my tank? I was looking for snails

My first thought was bladder snail on the left and ramshorn on the right.

I agree with Geoffrey.

If you put them in your tank they will breed. Not with each other but with other snails in the duckweed or snails which will hatch from eggs in the duckweed. You'll find most members either like these 'pest' snails or hate them. They become annoying if their numbers get out of control, and the usual cause of this is too much food. Over feeding the fish means left over food for the snails. Leaving dead plants matter in the tank means food for the snails. To stop them overpopulating the tank, keep the amount of fish food to a minimum; remove any bits of dead plant and clean the tank regularly. And remove any blobs of jelly you find as these snails both lay eggs in clear jelly.

Ok, I checked the duckweed and didn't see any more, but there are probably more. But they won't hurt the fish and tank, right? Thank you!

No they won't hurt, it's just unsightly if they have a population explosion. They are actually good as part as a tank's ecosystem; they'll eat things the fish and/or the fish keeper can't reach.

Essjay said:

No they won't hurt, it's just unsightly if they have a population explosion. They are actually good as part as a tank's ecosystem; they'll eat things the fish and/or the fish keeper can't reach.

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And they are a good bellwether. If you have a lot of them, then you're doing something wrong. Overfeeding is the big one. Not controlling algae is another.