Aquarium Fish Diseases

Aquarium fish diseases can be the bane of any fish keepers� existence. Coming home to find that you have sick tropical fish or even worse, dead fish is never a welcome discovery.

The simple fact behind the matter is that a lot of diseases can be prevented by taking proper care and keeping up a regular maintenance schedule. Our tropical fish rely completely on us to be cared for and kept healthy.


Velvet Disease

Part of keeping your fish healthy also requires that you minimise the stress that they are exposed to. Over stressed fish tend to pick up diseases easier as stress weakens the immune system.

It may interest you to know that almost every aquarium has some diseases in it already. By keeping your fish healthy they will be able to fend off these diseases and avoid getting sick or dying.

When it comes to aquarium fish diseases I always make the comparison to us humans and the common cold/flu. Prevention is better than cure and treatment is determined by focusing on the symptoms.

Prevention When Buying New Fish

Let�s start off at your local disease breeding ground, the pet shop. Now owners won�t like to be referred to like this, but fish arrive at these stores from various sources and don�t stay in the shop for very long.

Most diseases take some time to start showing visible symptoms and fish can be cycled in and out of the pet shop tanks before anyone knows that they are sick. Transporting from breeding farms to pet shops also cause the fish to stress which is not good.

As we mentioned, you may not be able to see any visible signs of aquarium fish diseases before you buy your fish. So you should look at how the fish are behaving in the aquarium.

Look at how active the fish are, sick fish often seem very lethargic and don�t swim around very much.

If possible, ask if you can see your potential fish feeding. Lack of appetite is another behavioural symptom that you can look for.

Once you have chosen a fish that is behaving well and has no visible signs of disease, you need to get it home while causing it as little stress as possible. The bag method works fine for short journeys, just make sure you go straight home and don�t stop off at the pub for 3 hours with your fish on your back seat.

I have noticed that fish seem to travel better in the dark. This is quite easy to achieve by covering the bag with a cloth or something similar while you are transporting it.

Not every aquarist is lucky enough to have a quarantine tank or hospital tank as some people call it. If you are one of the lucky ones, this would be the time to bring your quarantine tank into use.

It is a good idea to keep new fish in a quarantine tank for a few weeks before putting them into your main tank. Over these few weeks you will be able to determine whether any aquarium fish diseases are present. You will also be able to treat any diseases that may have been found.

If I don�t notice any disease symptoms after about 2 weeks, I would generally assume that the fish are safe to be released into the main tank. If I do find disease present then the fish will stay in the quarantine tank until the treatment process is completed.

Preventing Disease in an Established Aquarium

Proper maintenance is key in preventing your fish from picking up unwanted diseases. Probably the most important part of maintenance will be the regular water changes. Read our page on the Nitrogen Cycle to understand the importance of small water changes.

Besides prevention of nitrate poisoning, small water changes also help dilute other toxins that can build up in an aquarium environment.

Good hygiene can go a long way in reducing the risk of fish tank diseases. By this I refer to proper filter maintenance and thorough cleaning of your gravel etc. Making sure you remove as much decaying waste from your tank as is practical.

Ensure that your fish are properly fed. Make sure that you are feeding your fish the correct food. If a fish is underfed it will be weak and this will increase its chances of catching a disease. Over feeding fish will also add to the amount of decaying waste in the aquarium.

The incorrect living environment can also cause stress for the fish and promote disease. Things like this include water temperature, PH and hardness.

What to Do If You Find a Problem

Aquarium fish diseases rear their ugly heads from time to time, no matter how careful you are. What happens now depends on how quickly you spot the disease and how you react to it.

Should you see any of your fish showing disease symptoms, it should be removed straight away and placed into your quarantine (hospital) tank. Do this as soon as possible to prevent the disease from spreading and infecting all of your other fish.

Disease often indicates a problem in the water and the best way to determine the problem is with a water test kit. Test the water straight away so that you can rectify any issues before more fish become infected.

Don�t be scared if you don�t know what�s wrong with your fish. If you know the symptoms you can generally find out what the problem is. Certain aquarium fish diseases can be remedied simply by correcting water problems. Ammonia poisoning, nitrate poisoning and oxygen starvation are good examples of these.

If you have determined that your fish are affected by something other than common water treatment problems, then buying yourself some aquarium pharmaceuticals should be next on your list.

Observe the affected fish very carefully. Once you are sure of the symptoms then you can look into what medication you should buy. This is as simple as reading the label; each medication will list the symptoms that it will treat.

During the treatment process you should follow the instructions for the medication exactly, even if your fish look better after a day or 2.

TIP: While using medication to treat aquarium fish diseases, you should remove the carbon from your fish tank filter. Active carbon will remove chemicals from the water and these include aquarium pharmaceuticals. You want the medication to stay in the water so that it can treat the disease.

Disease Pages:

Ick - Ichthyophthirius Multifiliis

Velvet Disease - Oodinium Limneticum

Supporting pages:

Water Treatment

Fish Tank Filters

Fish Tank Maintenance

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