Basic Guide To Common Fish Diseases

We’ve all had that heart stopping moment when we glance at our tank and notice something wrong. Most fish keepers aren’t vets so diagnosing the symptoms and finding the right treatment can seem very daunting indeed. In this guide we’ll look at the most common issues and how to deal with them.

So what do we do when we discover an issue with our fish?

  1. Stay Calm!
    I really can’t emphasize this point enough! Take a moment and research the problem thoroughly before you do anything else! Diagnosing the problem and formulating the correct treatment plan is very important. All medicines are stressful to fish and bombarding them with the wrong products when they’re already unwell is only going to make things far worse. Medicines will only treat the issue for which they’re designed so don’t be tempted to use something just because you already have it on hand. Also switching from one treatment to another often involves large water changes and waiting for a period of time to pass for the previous treatment to wear off. This only adds to the stress and wastes precious time when we could be providing an appropriate treatment.

  2. Observe
    Take a good look at your fish. Look closely for any visible issues such as white patches, torn fins, bloat, bulging eyes, white spots, sunken bellies, or reddened gills. Look at their behaviour, there can be all sorts of signs that can help us to diagnose the problem. Are they gasping at the surface or flashing (scraping themselves against hard surfaces)? You may also find your fish struggling to swim normally or having trouble with buoyancy.

  3. Test the Water
    The first test is the easiest, check the temperature! It might sound obvious but it can often be overlooked in the heat of the moment (excuse the pun). Heaters can and do fail, some get stuck on causing the water to overheat and some fail completely causing the temperature to fall. Next you should test the water for ammonia and nitrite.
  1. Decide upon a treatment plan
    By this stage you might have already discovered the cause of the problem. If not then read on and we’ll discuss some basic issues and how to deal with them.

 So you’ve observed your fish and perhaps noticed some tell-tale signs but what do they mean? See the below list for a breakdown of the visual signs and what they can tell us.

  1. Fish Gasping Near the Surface
    This is often a sign that the water doesn’t contain sufficient oxygen. Warmer water is unable to contain as much oxygen as cooler water so it could be a sign that your heater has malfunctioned. Other causes are insufficient water movement. You can fix this by aiming the outlet of your filter towards the surface of the water to cause disturbance or even better, add an air pump and air stone.
    Another cause of this behaviour can be gill damage. If your fish have red or swollen gills then it’s essential that you test for ammonia and nitrite. If either of these levels are high then you should perform a large water change. If ammonia and nitrite are both reading 0 then it’s possible that your fish have gill flukes which are a type of parasite. This will require medication such as Interpet Anti Parasite Slime and Velvet 100ml
  1. White Patches
    Are the patches flat or fluffy? If the patches are flat then it would suggest a bacterial issue. This can be treated with King British Bacteria Control or Aquarium Salt. (Make sure that all fish in the aquarium can handle salt before dosing). Fluffy cotton wool like growth would suggest fungus. In this case I’d recommend Interpet Anti Fungus and Fin Rot 100ml

  2. Torn Fins
    This is often a result of aggression between tank mates. The best course of action is to remove the damaged fish and place it in a separate tank or breeder net to give it a chance to recover. If you have neither of these available then a fish net can be rested on the surface of the tank to provide a safe refuge until you can find a more permanent solution. You should continue to observe the fish to ensure the fins heal and don’t become infected. It’s particularly important to keep the water clean during this period. As a precautionary measure you could add a mild medication such as Interpet Disease Away, King British Disease Clear or API Aquarium Salt.
  1. Bloat
    A bloated belly can be a sign of a number of issues. The most common is constipation. This can be result of overfeeding or feeding foods that are very high in protein. Deshelled blanched peas are a great natural laxative for fish, another option is frozen brine shrimp. If your fish are refusing food then you can try putting them in an epsom salt bath. If those methods fail then it’s possible that your fish has an internal infection. Interpet Anti Internal Bacteria 100ml should help to deal with this. If the scales appear to be sticking out giving the fish the appearance of a pine cone then unfortunately this would suggest a case of dropsy which in most cases is incurable. It’s worth trying Interpet Aqualibrium First Aid Salt but you should prepare yourself for the worst.
  1. Sunken Belly
    If the fish displaying symptoms is a slow swimmer who shares his tank with much faster fish then it could be he is not getting enough food. Observe your fish when feeding to make sure this isn't the case. You may need to feed both floating food and sinking food at the same time. Also, feeding at both ends of the tank might help.
    Although under-feeding is a possibility, sunken belly is almost always the result of internal parasites which are particularly common with wild caught fish. A great treatment for this is Esha NDX. It’s also advisable to feed high protein foods to help your fish gain weight. Blood worms are a great source of protein but be sure not to feed too much as this could result in bloat.

  2. Flashing
    If your fish are constantly rubbing themselves against hard surfaces such as the gravel or décor then it’s likely they’re suffering from external parasites. In this case you should look closely for tiny white spots that look like grains of salt on their bodies. These spots usually start on the fins before spreading to the rest of the body. If white spots are present then Interpet Anti White Spot would be a good choice. If you can’t see any spots then it’s likely the fish are suffering from another form of external parasite that’s too small for us to see. A good choice of medication would be Interpet Anti Parasite Slime and Velvet 100ml.

  3. Buoyancy issues
    If you notice your fish struggling to swim normally, rolling onto their side or being unable to control their position in the water then it's likely an issue with their swim bladder. An ideal medication for this is King British Swim Bladder Control. It can be very difficult to cure this particular disease but treating as soon as you discover the symptoms will greatly improve the chances of the fish making a full recovery.

Hopefully the above information has helped you to identify the problem and decide upon a course of treatment. It is important that you continue to observe your fish throughout to ensure the problem is under control. It’s also essential to complete the full course of any medication used even if it seems that the problem is resolved before the full course has been administered. This is because many parasites and bacteria will enter a dormant state before being fully eradicated. Also, don’t forget to remove carbon from the filter as this will absorb the medication rendering it useless.

During treatment you may find that your fish refuse food. Don't keep trying to make them eat because you risk polluting the water which could make things far worse for your fish. They can go a very long time without food so don't worry too much, they'll soon start eating again once they're feeling better.

This blog doesn’t cover every disease but will hopefully cover most issues that you’re likely to encounter. If you have any question then leave them in the comments below or contact us for further advise.


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