The main reasons for the bloated belly of Siamese fighting fish are as follows:
Dropsy: Dropsy in Siamese fighting fish is a serious disease, characterized by abnormal abdominal enlargement. In the later stage, it may be accompanied by pinecone scales and protruding eyes. The causes of dropsy include unclean fish food, irritation from low-quality feed, internal parasitic infections, or organ failure due to a weakened immune system.

Tumor: If the belly of the Siamese fighting fish bulges unevenly, it may be caused by a tumor.
Constipation: If the Siamese fighting fish doesn't defecate after the last feeding, the bloated belly may be due to constipation.
Diagnosis and Treatment Methods:
Treatment for Dropsy: The treatment of dropsy mainly relies on antibiotics, such as kanamycin, tetracycline, chloramphenicol, streptomycin, and kitasamycin. You can dilute the antibiotics and add them to the water for a medicated bath, or directly feed the fish with a dropper, or add them to the feed. For internal bacterial diseases caused by bacteria in food, in the initial stage, gentamicin or furazolidone + oxytetracycline can be used, supplemented with magnesium salts or allicin for treatment.
Improve Water Quality and Reduce Feeding: If the problem is caused by water quality issues or spoiled bait, you can improve the water quality, reduce the feeding amount, or even stop feeding temporarily.
Internal Deworming: If an internal parasitic infection is suspected, internal deworming drugs can be used for treatment.
Preventive Measures:
Control Water Quality and Water Temperature: Keeping the water quality clean and maintaining an appropriate water temperature can effectively prevent dropsy.
Feed Reasonably: Set a fixed amount of food and avoid overfeeding or feeding unclean food.
Regular Inspections: Regularly check the health status of Siamese fighting fish, and promptly detect and deal with problems.