If your goldfish is swimming around with their mouth open, it may be another sign that they are having difficulties getting enough oxygen.
Similarly, make sure your goldfish is swimming around and interacting with things in the tank. If your goldfish is hardly moving and staying right at the bottom of the tank, it’s a sign that something may be seriously wrong with them. [4] X Research source
Look at your goldfish’s fins for any tearing or red veins that are bulging out. This is normally a sign of stress or could be an indicator that there is another fish in the tank that is bullying them. Make sure the fins are at their full length and not starting to shrink or deteriorate into a stump. If any part of your fish’s fins seems to be disappearing, it could a sign of fin rot. Black spots might mean that your goldfish has ammonia burn or some type of parasite. Make sure your fish isn’t bleeding or missing any scales. If you notice any small red marks on your fish or any spots in its skin without scales, something is hurting your fish. It could be another, more aggressive fish in the same tank, or it may be your fish rubbing against something to try and scratch a parasite.
Look for a fine white fuzz, particularly around the mouth, or any other discoloration of the scales. This could be a sign of a bacterial infection that will need to be treated. See if you notice any small, white or black spots on your fish. White spots may indicate that your fish has ich, which is a common parasite found in goldfish. Check for bloated or raised scales. If you see any bloating or protuberance where you’ve not seen one before, it could mean that your goldfish is ill. However, it may also mean that they’re pregnant, or that you’ve just been overfeeding them.
Protruding eyes may be a sign of “pop eye”, which is usually caused by an infection. Cloudy eyes, or eyes with a cloudy film over them, can be a sign of some sort of vitamin deficiency.
If you notice that your fish isn’t eating, try sprinkling a little food so that it falls right in front of them. It may be that they can’t see the food or are slow to react to it, this is another sign that something is wrong.
If you have more than one fish in a tank, you should immediately quarantine the unwell goldfish in a hospital tank. If your goldfish is suffering from an infection or parasite, keeping it in the same tank may let the illness spread. Sometimes a change of water is all your fish needs to start getting better.
If you have high levels of ammonia or nitrates in your water, you should clean it out and replace it with new water immediately. Keep an eye on the ammonia levels in your water to make sure they stay at a reasonable level. If your filter pump is having difficulty keeping up, try cleaning it thoroughly, or replacing ¼ of the water every day to help it out. If there’s not enough oxygen in the water, you may need to replace or repair your air pump to make sure your fish can breathe properly. If you don’t want to buy a freshwater test kit, you may be able to take a small vial of water to your local pet store and get them to test it instead.
There may be rotting food or other damaging things in the gravel at the base of your fish tank, so make sure it is cleaned completely.
You can use tap water to refill your tank, but make sure it has been properly treated with a water conditioner before using it. It may pay to test conditioned tap water to make sure it will be OK for your fish. [12] X Research source If the water in your tank is too warm, add some chilled water to lower the temperature to one that will suit your goldfish. Goldfish will normally thrive in water around 23 °C (73 °F). [13] X Research source
Ich is a parasite that may infect your fish, which will look like small white grains of salt on its scales. You can treat ich with aquarium salt, or formalin treatment which is used as an ich treatment and available from your local pet store. Fin rot and swim bladder are both fungal infections and can be treated with a fungus eliminator. If your goldfish has a parasite, you can treat it with a parasite guard, which should be available at your local pet store or online.
You will likely need to transfer your fish to a plastic bag of water or a smaller bowl to transport them. Cover the bag or bowl with a paper bag or something similar so that the fish doesn’t get stressed while being carried. [16] X Research source
Take comfort in knowing that you did everything you could to try and save your goldfish and that you took care of them as well as you could. Consider getting a new goldfish when you are ready.
