What is the fine-grained topic of the following text: All sorts of fishy goodness in it that would otherwise go down the drain, it's a treat the kitties get in direct proportion to the number of times I decide my desire for the perfect tuna sandwich (on toast, with minced onions and garlic dill pickles mixed into the salad) outweigh my concern over mercury poisoning. Only return the topic.
Feeding cats with leftover tuna from making tuna sandwiches