DROPSY in fish; prevention, causes, and possible treatment of this malady that is often a symptom of other problems.



(This question is from a forum post I responded to)
QUESTION: I posted about a female Siamese fighting fish that appeared to have dropsy a few weeks ago. I treated her twice with Maracyn. After the swelling didn't
start to go down, but she is still as swollen as she was then, but has not got to the point were her scales have started to protrude? Does anyone know what else that it could be. She seems buoyant and the swollen cavity appears to be filled by either air, of a clear liquid, when she swims in front of the lights?

ANSWER:
Have you tried Kanacyn? Maracyn (Erythromycin) is usually not as effective for most causes of Dropsy (since most bacterial causes such as Aeromonas are gram negative and Erythromycin is gram positive).

Dropsy is generally a symptom of something else, sometimes digestive, often kidney or liver related and can be loss of regulation of electrolytes (which is another reason for good trace element levels; please see these two articles: Calcium, Electrolytes, GH, KH, & more, Do Fish Drink; Proper Osmotic Function ).

Because of this, Dropsy can often be very difficult to treat, especially if caught in an advanced case in the fish. What the aquarist often observes is a “pinecone” swelling generally caused by fluid building inside the body cavity (often involving the Kidneys), for this reason, reducing this swelling is an important step in effecting a cure.
I have heard of Minocycline also being recommended for this. I do not recommend this as Minocycline has been shown to cause serious damage to the kidneys, which is the last think you want to do to a fish suffering from Dropsy or even suspected of this malady.

I would also note that since Aeromonas bacteria is a common cause of Dropsy and since this bacterium is anaerobic, maintaining good circulation, aeration and overall good tank hygiene goes a long ways in treatment and even further for prevention (since Dropsy is difficult to treat and cure). Please more about optimum tank condition in the prevention section further into this article.

This said, besides treatment for a possible underlying infection, you want to take steps to remove the swelling.

Here are the steps I would take (these apply to ALL fish, not just Bettas):

*Change water! (25% should be fine)

*Perform a medicated bath with Methylene Blue and Kanacyn. To prepare this bath I use 1 teaspoon 2.303% solution per 5 gallons (double dose) in a bath of aquarium water from the tank the fish you wish to treat came from, I usually use about a ½ gallon of water, however you may use less. Measurement of the Methylene Blue does not need to be precise as this bath should be used for about 30 minutes (although do NOT overdose). Make sure you keep the water in a warm area, as in a cold room the water temperature can drop rapidly which would stress the fish. As to the Kanacyn, I generally have used twice to four times the recommended in tank strength in these baths of Kanamycin.
You also may add salts to this bath as well at about double tank strength; 1 teaspoon sodium chloride per gallon and 1/8 to ¼ teaspoon Epsom salt per gallon of bath water.

Do NOT pour this water back into your display aquarium when finished. This can be performed twice per day.


*Add one tablespoon of regular salt (sodium chloride) per 5 gallons of tank water and ¼ to ½ teaspoon of Epsom salts per 5 gallons of tank water. Add a Wonder Shell or similar product to add needed calcium. What these minerals will do is add electrolytes and change (and improve) the osmotic balance of the fish vs. the surrounding water to hopefully pull fluids thru the body thus reducing swelling. For more about electrolytes, please read this article: Calcium, Magnesium, and KH in Aquariums; How to maintain a Proper KH, why calcium and electrolytes are important.

*Treat tank water with Kanamycin (Kanaplex), or possibly with Neomycin or Nalidixic Acid.
Also consider feeding the infected fish with fish food soaked in Neomycin such as Aquarium Products Gel Tek Neomycin along with in tank treatment of Kanamycin (hospital tank is best). Other treatments of note are Minocycline (Maracyn II) and possibly Metronidazole (SeaChem makes an excellent pure Metronidazole).
Sometimes a “cocktail” approach with more than one medication is necessary for Dropsy, such as Kanacyn and Metronidazole together (and this still includes the baths!!)

Here is more info about aquarium medications:
AQUARIUM MEDICATIONS; treatments, how they work, and which ones to use and not to use


PREVENTION:

The aeromonas bacteria (that is often present in healthy aquariums) can cause infections that will manifest this way in poor water conditions, especially in aquariums with poor circulation and high amounts of DOC (dissolved organic compounds) s Aeromonas Bacteria are anaerobic and thrive in low oxygen, high dissolved organics conditions. So maintaining a healthy aquarium with regular water changes, good filtration (if possible, this is why I see more cases of Dropsy in Betta kept in a bowl), good feeding practices (not over feeding and using quality foods), and maintaining proper water parameters (ammonia and nitrites 0, kH 80 ppm, nitrates under 40 ppm). A water parameter that is often missed (as the more obvious ammonia and nitrites are usually noticed) is proper calcium and electrolytes. If RO or drinking water that is nothing more than RO with a few minerals added for “taste” is used, there are usually insufficient electrolytes and calcium for proper osmotic function and fluid retention can result, which will then lead to kidney infections. Please read these articles for more about this: Proper Osmotic Function, AND/OR CALCIUM, KH, AND MAGNESIUM IN AQUARIUMS; How to maintain a Proper KH, why calcium and electrolytes are important.
All this goes a long way in prevention of Dropsy and other diseases.

A proper diet makes a large difference here. Do not feed your fish meat based proteins, I recommend aquatic based proteins such as white fish meal, shrimp or even the proteins found in spirulina algae.


As a basic diet I recommend Sanyu or Hikari Betta Gold (there are many other quality foods as well, although I do not recommend flake foods for bettas as their staple diet)
Poor quality proteins (or better; unusable amino acids for fish) can lead to digestive problems or Renal failure, which CAN lead to the symptoms of Dropsy.
All proteins are made up of amino acids, some are usable (by fish), and some are not.
Those that are not are disposed of by kidneys in the fish. This can lead to renal failure or infection. For more information about proper nutrition, see this article: "Quality Fish Food; What ingredients are needed for proper fish nutrition, growth and health". Also always soak all dry foods in water for 5 minutes prior to feeding as this will remove air that can lead to infections of the digestive tract (this is best for ALL fish, goldfish in particular).
I would recommend this as a basic diet for your Betta: Sanyu Betta Gold

To summarize prevention; I have seen very few cases of Dropsy in the literally 1000s of aquariums I have maintained over the years (I have seen many cases of Dropsy when non service customers call me out to see why their fish are sick and I often will observe very poor water conditions), that is because I have always maintained my tanks with regular cleanings, proper electrolyte levels, a reducing Redox and often UV Sterilization.
I highly recommend reading this article about Disease prevention for more about this subject: “Aquarium Disease Prevention”

Fish Anatomy For further help in understanding the anatomy of fish (so as to no where the Kidneys are located), please read this article.