My stingy usually enjoys earthworms as its main diet and usually accepts a variety of foods like frozen fish, shrimp, scallop, and squid, but lately she won't eat anything but ghost shrimp. She seems to try and eat the worms but then either they crawl out of her stomach somehow or she throws them up. The ghost shrimp are really a last resort because I don't want her to get a parasite of any sort, plus its putting a pretty big dent in my wallet. The water quality is good: ammonia 0, nitrite 0, nitrate below 10, ph at about 7.2 and 0 chlorine. Any idea why she would do this? She's a female yepezi around 6 inches. Thank u in advance