Is there a message size limit with elliptic-curve-based public-key encryption? There's a lot of discussion and answers regarding RSA's limits when it comes to the size of the plaintext, but I couldn't find anything similar when talking about ECC.

Is there a limit? If so, why and what is it?
Is there a limit?


Depends on what ECC encryption algorithm you're talking about.  ECC really means 'lets use elliptic curves to do cryptography', there are several ways to do that to do public key encryption.

If you use EC-ElGamal (which is just ElGamal translated to use Elliptic Curves), you're pretty much limited to the group size; you're encoding a EC point, and so you're limited to the number of EC points there are.

On the other hand, if you're using ECIES, there is no effective limit.  That's because you're not really encrypting the message with the curve itself; instead, you're using ECC to transport a one-use symmetric key, and then using that symmetric key to encrypt the message (and so the only size limitation would be the limit of whatever the symmetric algorithm you're using has).