Why two bites won't upset your senior cat
At 14 pounds, your cat's size means those two small pieces of plain herring are barely a snack. Cooked fish without seasoning or oils is generally safe for cats in tiny amounts like this. The real concern would be if she'd eaten a whole fillet or something with added ingredients, but here we're talking about a few shreds of fish.
Since your kitten didn't eat any, you only need to monitor the senior. Cats can sometimes react to new proteins, but two bites are unlikely to cause more than a slight stomach gurgle. Her age alone doesn't change the risk with such a minimal amount.
What to watch for over the next six hours
While problems are improbable, keep an eye out for vomiting or unusually loose stools. Some cats get excited about fish and eat too fast, which can cause regurgitation unrelated to toxicity. True food reactions usually show within 4-6 hours if they're going to happen at all.
If she acts normal—no hiding, no refusal of her regular food, no excessive licking at lips—you can assume this was just an unplanned treat. Multiple pets mean watching who ate what, but in this case, only one had access, which simplifies things.
When a senior cat's diet matters more than the fish
At her age, the bigger question is whether she has any known kidney issues or food sensitivities. Plain herring isn't a common allergen, but cats with chronic conditions might react differently. If she's on prescription food, check whether fish is restricted in her diet plan.
Two bites won't throw off her nutrition, but it's a good reminder to keep human foods out of reach. Kittens learn from watching seniors, so next time both might dive for the fish. A 14-pound cat carrying extra weight could also do with fewer extras, even harmless ones.
Why this differs from raw or seasoned herring risks
Cooked plain herring lacks the thiaminase enzyme that makes raw fish dangerous over time. You're not dealing with bones either, since cooked fillets usually have them removed. What your cat ate is essentially the same as commercial cat food's fish ingredients, just less processed.
Compare this to pickled or smoked herring, where salt and spices become the hazard. Two bites of those could warrant a vet call, but here the only variables are the fish itself and your cat's individual tolerance—both of which point to low risk in this tiny quantity.
The full verdict, portion guidance and serving notes are collected on the Herring food facts page.