Is Ceratophyllum demersum toxic to cats?

Mildly. The ASPCA lists ceratophyllum demersum as mildly toxic to cats — a chewing cat typically gets mouth irritation, drooling, and vomiting rather than a medical emergency, but it is still best kept out of reach. Ceratophyllum demersum is not individually listed in the ASPCA Toxic and Non-Toxic Plants database, so its pet status is not formally established; treat as uncertain and verify with a vet before assuming it is safe to ingest. It is widely kept in aquaria with no documented toxic principle, but absence of an ASPCA listing is not a safety guarantee.

Ceratophyllum demersum is not individually listed in the ASPCA Toxic and Non-Toxic Plants database, so its pet status is not formally established; treat as uncertain and verify with a vet before assuming it is safe to ingest. It is widely kept in aquaria with no documented toxic principle, but absence of an ASPCA listing is not a safety guarantee. Signs usually appear soon after chewing rather than hours later — watch for drooling, pawing at the mouth, vomiting, loss of appetite, or unusual lethargy after your cat has had access to ceratophyllum demersum.

Stay calm. Remove any plant from your cat's mouth and take the plant away. Note how much was eaten and when, and do not induce vomiting unless told to. Call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 and follow their advice; a leaf or photo helps the vet treat it correctly.

The ASPCA classification Growli uses applies to both cats and dogs: Ceratophyllum demersum is mildly toxic to dogs as well. See the full ceratophyllum demersum pet-safety guide for both species.

For a similar look without the risk, see the best cats-safe plants list — every plant there is ASPCA non-toxic to cats and dogs.