Understanding Dropsy...

[Jubs]

Well I see a lot of cases of Dropsy on here and I also see a lot of misunderstood explanations for the cause. I will attempt to help ease the confusion and try to keep this as simple as possible. I am not an expert by any means but I have done research on this over the years and I will be using a great book on Fish Diseases as a reference to better explain the disease.

Dropsy what is it...

"Dropsy is not a disease in its own right but a symptom or sign that can come about from a variety of different diseases and disorders. Unfortunately, in many hobbyist texts and on proprietary treatment instructions, it is often erroneously considered to be a distinct disease into its own right." Lance Jepson (from reference book that will be added at the bottom of the article)

"...in many hobbyist texts and on proprietary treatment instructions, it is often erroneously considered to be a distinct disease into its own right." I couldn't agree with this more! Having had issues with this in the past I just wasn't satisfied with the "it's Dropsy" well I wanted to know what causes it as I never got a straight answer to what the reason for it was. So lets take a look at what Dropsy really is...

The symptoms of Dropsy are better termed ascites and oedema. New words, eh? Well let me explain what they mean and it will make sense if you have dealt with Dropsy in the past.

First, lets look at the term ascites. Ascites is a condition where there is a build up of fluid inside the body cavity also known as the coelom of the fish. When this happens this where you start to see swelling, bloating, or whatever term you want to use of the fish's body and is also a sign of other diseases. What is happening when this fluid is collecting in the body cavity or coelom is it is building up pressure with in the fish's insides. Well what happens then? Well, with that pressure it is in turn putting pressure on the internal organs and blood vessels restricting them from their normal function. I don't know about you but you don't have to be a genius to put figure this one out and realize that this can cause major problems.


Now lets look at the term oedema, this is when the fluid collects in the fish's tissue. Here's the main one everyone is going to recognize when they think of Dropsy. When oedema occurs it is building up fluid in the microscopic areas of tissue surrounding the scales, making sense yet? Well this is where you get the "pineconing" effect,the raised scales on the fish. Pineconing is the most common sign for people to point to Dropsy as a diagnosis.

What is causing the symptoms?

Ok, so know we know what these terms mean now, but why is this happening? I will try to explain this without getting into another good article topic in itself. When you hear the word osmosis most people think of reverse osmosis and RO water well that's not the only thing osmosis refers to it also plays the role of how fish live in water.

Well lets take a look at the definition of osmosis: "Osmosis is the diffusion of water through a cell wall or membrane or any semi-permeable barrier from a solution of low solute concentration to a solution with high solute concentration, up a solute concentration gradient. It is a physical process in which a solvent moves, without input of energy, across a semi-permeable membrane separating two solutions of different concentrations." (According to Wikipedia)

So what does this have to do with Dropsy? To answer that when it comes to the build up of bodily fluids, examples blood and lymph fluid in the body cavity (coelom) of the fish (ascites) and the build up in the tissue of the fish (oedema) is from a malfunction of the osmoregulation system of the fish. What happens with this system is fish are equipped with a semi permissible barrier or osmotic barrier of their own in which they use to regulate the concentration of proteins, salts and hormones with in the body of the fish. What is happening is the osmotic barrier is permitting the surrounding water to enter the body and dilute these concentrations. The osmotic barrier is made up of the gill tissue and the skin of the fish. Water is constantly in contact with their osmotic barrier and regulated by the osmoregulation system which is made up of the gills, kidneys, and with a lesser important role of the intestines.

So if their is damage to these to these organs it will cause a malfunction in the osmoregulation system which will cause the build up in the concentrations of the fluids stated above. The concentration levels within the body of the fish needs to be controlled within very close parameters, so when there is damage to the osmoregulation system this causes the imbalance of the concentration levels to the body fluids. When the concentrations are out of whack this causes ascites and oedema to occur.

The underlying diseases to cause Dropsy

Basically the cause for Dropsy comes down to any disease that causes interferences to the osmoregulation in freshwater fish and cause ascites and oedema in the fish. I will quote my reference book for the common examples of diseases that interfere with osmoregulation and will cause the signs of Dropsy.

"Any disease process that interferes with osmoregulation in freshwater fish can result in overall accumulation of fluid in the fish that will, in turn, manifest itself as the signs of dropsy.Common examples of these are:

• Heart disease
• Liver disease
• Gill disease such as ectoparasites (like Dactylogyrus)
• Bacterial gill disease and fungal infections
• Kidney diseases, including mycobacterial infections (fish tuberculosis)
• Protozoal parasites like Hoferellus carassii in goldfish
• Noninfectious disorders, such as polycystic disease, again in goldfish
• Gut disorders, including severe parasitism by worms or protozoa (for example, coccidia)"

What to look for
Well now that we understand what the real cause for Dropsy is now lets take a look at what to look for. Of course there is the classic "Pineconing" or oedema. Some other signs to look for are ulcerations, hemorrhaging, loss of balance due to pressure on the swim bladder, as well as strenuous breathing are all possible symptoms to look for. Note that other than the oedema the other symptoms are also common symptoms of other common diseases, which brings us to...

Here is the real kicker and one that is most commonly misunderstood! "Remember that "dropsy" is only a sign of disease , and consideration must be given as to what the underlying problem is. Do not stop at dropsy as the diagnosis- investigate further to try to find out why it is occurring. Dropsy is not a diagnosis in its own right!"(Direct quote from reference book)

Treatment

The first thing to do is try to find the underlying problem(s) and treat them accordingly! I will advise you do this in a hospital tank with the fish effected fish isolated from other tankmates for obvious reasons. As you can see in the above text Dropsy is not so much a disease per say but an effect or side effect from another disease and has damaged the osmoregulation system. This in turn has caused osmosis irregularities within the fish's body fluid concentrations. So in order to attempt to correct the osmotic irregularities we need to reduce the concentrations within the fish we need to adjust the osmotic concentrations outside of the fish as well (the water the fish is in).

How we do this is with aquarium salt or sea salt added to the freshwater to make an ideal concentration of 0.3% salt solution or "30g (around 2 tablespoons) of salt to every 10 liters (2.6 gallons of water) of aquarium water." (quote from reference book) The book also mentions the use of a syringe to draw off internal fluid but also mentions several of the risks as well, seeing as most of us aren't qualified to attempt this I will leave this procedure out. 

Final notes on treatment

As most of you know that have dealt with this in the past know that once the signs of Dropsy have shown themselves the fish is pretty bad shape and the odds of recovery are slim. You can try your best to help the fish recover with the salt solution method in addition to treatment of the underlying disease and cause of Dropsy, if this fails or you feel its just too late it is best to humanly euthanize the fish. Several methods for humane euthanization can be found with a little research.

Finally note, there are several other disease that can cause some of the signs of Dropsy such as internal hemorrhaging, swollen abdomens, etc. so be sure to properly identify before you diagnose any disease (many of which can be avoided by proper water quality and diet) before you start a treatment as improper treatments can cause unneeded stress and lower your odds to saving your fish. 


Reference credit:
Jepson, Lance, The Super Simple Guide To Common Fish Diseases, TFH Publications 2004

[ShieldWolf]

Very informative without getting too technical with the verbiage. Great write up.

[helenf]

Very informative without getting too technical with the verbiage. Great write up.

Agreed. 

This should be an article or a sticky post. 

[Lori]

Bravo, Jubs!  I'm going to sticky this.  Thanks for the time and excellent write-up!

[Jubs]

No problem guy's I just noticed a lot of dropsy posts and I figured instead of answering them I would help people understand it instead. I hope this will help some people and that alone is worth the time spent on it.

[wendyjo]

So instead of salt making the fish retain water, like it does in humans, it can actually be beneficial?  I was always told NO SALT if treating dropsy because of this.

[Jubs]

So instead of salt making the fish retain water, like it does in humans, it can actually be beneficial?  I was always told NO SALT if treating dropsy because of this.

Yes like I said in the post fish osmosis is a whole other article, I will break it down very simply and crudely though. Freshwater fish try to retains salts internally where as saltwater fish try to retain more freshwater internally. That is a very vague description but it gives you the idea.

[Lori]

Where is that, wendyjo?  You're right, regular salt will pull fluids into the tissues, causing increased bloating.  It's epsom salt that should be used.  

Is that what you meant, jubs?

[Jubs]

Where is that, wendyjo?  You're right, regular salt will pull fluids into the tissues, causing increased bloating.  It's epsom salt that should be used. 

Is that what you meant, jubs?

The idea behind it that is the fact that when the dropsy is happening the fish's ability to absorb water and level out the concentrations internally (osmosis) is flawed so therefore you are trying to match the surrounding water to the internal fluids it's retaining in hopes it will make it easier for the fish to balance the concentrations. Basically you are assisting the fish in the process of osmosis, and making it easier for it while you are trying to get to the root of the problem aka the real disease that has caused the dropsy. 

[Lori]

Exactly, Jubs!  But while trying to maintain osmotic balance, the bloating is caused by an imbalance.  By adding regular salt, this will pull more fluid from a lower to higher concentration.  That's why epsom salts work here.  MgSO4 actually helps return the fluids to the vessels rather than pulling them into the tissues causing even more of an osmotic imbalance.  This is called "third spacing" of fluids.