This disease needs to be discussed in depth. This is a bacterial infection.
Dropsy is very difficult to treat and at times this will lead to the death of your treasured betta fish.
This is one of the most disfiguring. It will show a very swollen belly which is out of the ordinary and the scales will be protruding excessively.
This would have not happened in the first place if you have regular water changes and proper nutrition for your betta.
The betta fish care is outlined on this article.
It is believed that it is a bacterial infection.
The bacteria will first invade the kidney which will cause the betta fish to retain fluid.
The retention of the fluid will cause the betta fish body to bloat.
So where did the bacteria comes from ?
This is not having regular water changes and poor water parameters.
Feeding excessive live foods may also be a culprit since you need to absolutely know where the live food source is coming from. It has to be clean and free from bacteria.
I myself feed my betta fish in the form of pellets and frozen food which is very safe and hygienic.
Too many tank mates will cause stress to your betta fish and can be the source of dropsy too.
The most obvious sign of dropsy is the disfigurement of your betta fish.
It has a severe bloating on the stomach in which the scales will be protruded causing it to look like a pine cone.
It doesn’t seems to have any appetite at all, always gasping for air and motionless.
First and foremost is to have a 25% water change every three days just to make sure that the water is clean and hopefully stop the infestation on the fish tank.
If you can purchase a 10 gallon nitrogen cycled fish tank.
If you noticed that there are some fishes that is affected with dropsy then try to put it also in the hospital tank together with the betta fish.
You have to leave the affected fishes in the hospital tank for two weeks hoping that they will recover and treated.
Try to give the original fish tank some treatment as well as probably they are at the initial infection stage.
Medicines that are recommended : tetracycline, kanacyn, maracyn and neomycin.
Keep the water level a little lower than normal so that it may be helpful for the betta fish to go to the surface easily
Add some air pump aerator so oxygenate the fish tank.
It is essential to add some aquarium salt at around 0.5 teaspoon per gallon on the hospital tank to stop the swelling and release the fluid build up.
The antibiotic normally removes the oxygen in the fish tank so it is best to make a 25% water change every day when you are treating your betta fish
When you are administering the medicine in the hospital tank it would be best to keep it bare.
Just the betta fish in the hospital tank with air pump without any plants or any other fish tank mates if possible.
You should not use the hospital water for your main fish tank since it contains strong medicine and can disturb the normal bacteria cycle on your fish tank.
It would be a miracle if your betta fish survives this strong medicine because the kidneys and liver will be in severe stress when the medicine is working on its way to your betta splendens.
Sometimes if you feel that the betta fish has to end its life humanely then use clove oil and vodka.
Here is a link : What is the most humane way to euthanase aquarium fish?
I have mentioned many times that in order for your betta splendens or any other fish not to contract any form of ailments and disease then you always have to follow proper water parameters and proper food feedings.
If you just follow the water changes as often as once a week. There will be no problems with your betta fish.
The dropsy will be contracted if you keep your betta fish in 2 gallons or fewer fish tanks because the betta splendens waste excrement will be cycling in the water bowl and the fish is living in its own waste.
The recommended fish tank will be around 5 gallons or better yet a 10 gallons fish tank with heater and filter in place.
The best setup will be an aquaponics system wherein a 5 gallon is enough for the betta fish since the roots of the plant will voraciously eat the ammonia and nitrates inside the fish tank.
The plant actually needs the ammonia and nitrates in order it to grow.
If you have an aquaponics system then it will be a symbiotic relationship between the betta fish and the plant.
Actually you don’t even need to follow the regular 25% water changes, just add water when it evaporates.
Sometimes, if you put too much food and there will be toxic ammonia build up which you need not worry about since the plant is there to take care of the clean up.
Here is a link on an aquaponics setup.