Fish Bite

Periodically our pet Midas fish will lay eggs. Since she lives alone (because she will kill other fish), the eggs are infertile and I need to clean them out. The last time I did that she was actively guarding them and bit me! We've had this fish for 11 years; and I don't know how old she was when I bought her. She used to be in a bigger tank with other cichlids but when we moved a few years ago we put her in a smaller tank and she has not grown since then. She likes to hide in her coral a lot of the time and seems to be fine in the smaller tank.