The Aquarium Guide

Dropsy Fish Disease – Symptoms, Prevention and Cure

The most engaging problem fish keepers’ face is dealing with fish diseases. If the symptoms are not detected and dealt with at an early stage, depending on the type of bacteria or infection, all of the fish in your aquarium might die in a single swoop. One of those problems is the Dropsy fish disease.


The word ‘Dropsy’ derives from an ancient word in French – hydropse, which is based on a word formed by the Greeks – hydrops that is derived from hydro or its English meaning – water.


The Dropsy fish disease exists since fish keeping started out basically, that’s why the name is so old. If we would discover the Dropsy fish disease today, we would probably name it the “Edema fish disease”. The disease targets the insides of its target and creates a swelling in the abdomen, mainly because of accumulating water in the fishes belly.

Dropsy Fish Disease

Dropsy Fish Disease in Aquariums

The Dropsy fish disease is more like a ‘health issue’, then a disease. It is like a combination of symptoms due to a decrease of the immune systems stability in the fishes within the aquarium. There is a bacteria that all aquariums have it and if any or all fish are somehow stressed from anything at all, from an environmental change or missing a feeding schedule, even being bullied by other fish, the immune system starts failing and the bacteria does its work. The belly starts dropping down and the fish who had contracted the bacteria appear like they are bloating. If the fish are healthy and thrive in a healthy environment without any stress factors, there is no danger in contracting the Dropsy fish disease.

Dropsy Fish Disease Symptoms

The characteristically swollen belly of the Dropsy fish disease is the last thing you want to notice in your fish. It means the internal organs are injured and the belly of the fish started to fill itself with water and other fluids, leading to the fishes ultimate demise. In this stage, even with a fast medical response, it is more likely the fish will die. Some fish do not show any other symptoms at all, but there are a couple of symptoms that are visible to the human eye and if noticed on time, you can prevent the spreading of the Dropsy fish disease and even save the ones who are actually infected.

External symptoms are easy to detect, if the fish are showing them, like when the scales are standing out like a pinecone, have swollen eyes, pale gills, swollen anus with a bloody coloration, pale feces, a curved spine, clamped fins, lethargic movement (this is when the fish just hover near the top of the tank instead of swimming), losing their appetite and etc.

All of these symptoms progress aggressively, so if you notice even one of the mentioned-above, start reacting accordingly.

How to treat the Dropsy Fish Disease

If you ask someone what to do with the infected fish, most will advise you to euthanize them so the healthy fish can be safe from the infection. But if you detect the disease in its early stages, there is a possible treatment that can save the infected fish with Dropsy fish disease.

This what you can do:

How to prevent an outbreak

Like all bacterial infections, the best way to prevent them is a healthy and clean environment. Fish are quite prone to stress, and when they are stressed, their immune system fails. Maintaining a clean aquarium is a priority for all fish keepers, because low quality water is the number 1 stress factor for fish. Change the water regularly, maintain a clean fish tank, clean filter, do not overpopulate the aquarium (get another fish tank or create a larger aquarium) and be mindful of what, when and how much you feed your fish. Keep track of the foods shelf life; if you open a flakes package, use it within a month. Don’t feed them with a single food source, a healthy diet consists of freshness and variety.

Causes of the Disease

The nasty little bugger that causes the Dropsy fish disease is a bacteria called Aeromonas. It is a common bacteria, found in almost every aquarium. It is a “gram-negative bacteria” because it can be identified with a Gram Staining technique.

The Aeromonas can lead to the Dropsy fish disease only if the immune system of the fish in the aquarium is already failing.

This can happen if the fish are under stress by any number of stress-factors:

Basically the Dropsy fish disease thrives in an environment where there is at least 1 stress factor. If your aquarium is stress free, you have nothing to worry about.

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