However, I can tell you that there are a few possible reasons why a real neon fish might have a bubble on its mouth:
* Constipation: If your neon fish is constipated, it could be straining to pass waste, which might lead to a bubble forming near its mouth.
* Air swallowing: Neon fish might accidentally swallow air while eating or being startled, which can also cause bubbles around their mouths.
* Parasites or disease: In some cases, a bubble near the mouth could be a sign of a serious health issue like a parasite or disease.
If you see a bubble on your neon fish's mouth, it's essential to observe its behavior and consult with a veterinarian who specializes in fish. They can help determine the cause of the bubble and recommend the best course of treatment.