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Like all living things, fish also get sick. These animals are not as expressive as cats or dogs, so it is very important that you know the routine of your fish so that you can detect any disease in time.

Has your fish started behaving differently and are you worried? In this article from Guppy’s Aquarium Products we will talk about the 8 symptoms of a sick fish and, above all, what to do when they appear.

  1. Your fish does not unfold its fins

If your fish remains floating in the aquarium and does not deploy the fins, it may be incubating a disease that is not showing any other symptoms yet, so monitor it for a few days.

It could also be that you are suffering from stress. Large changes in the pond, such as a general cleaning, a change of plants or toys, or that the aquarium does not have enough space for each fish, are some of the causes of stress. Pay special attention to this, as it is capable of causing the death of your pet.

  1. Your fish is at the bottom and not nothing

If your pet swims slowly or gasps, it is possible that the pH of the water is very high, this can be very dangerous for any species of fish, since each requires that the water be in specific conditions to survive.

If you notice that your fish behaves this way suddenly, check the water conditions before ruling out another disease.

  1. Your fish stays on the bottom side

The causes of a fish staying at the bottom and with a side position are varied. Most likely, the water has a very high concentration of NO3. If this is the case, you should place fast growing plants and other floating plants.

In these cases, it is also possible that the fish has a vision problem or has become blind, so it is not unable to maintain balance, being another of the symptoms of a sick fish.

  1. Your fish does not move but breathes

If your pets breathe, but their movement is poor or almost nil, it is likely that they have an infection. The causes of infections in aquariums are varied: a bacterium may have infected the water or plants, there is some other sick or dead fish, the water conditions have changed, promoting the growth of bacteria, among other reasons.


If you observe this behavior, check the state of the water and pay attention to any change in the appearance of your pet.

  1. Your fish rubs against the objects in the fish tank

If your fish is continually rubbing against objects in the pond, it may have some kind of external parasite. These parasites are usually very annoying, so you will quickly notice changes in the behavior of your fish. See if your pet has reddened gills or white spots along its body.

However, if this behavior appears after the fish has been manipulated with a net or with the hands, it is not something serious, it will pass quickly.

  1. Your fish does not eat

If you notice that your fish has no appetite, this can happen for three reasons. The first of them is that you are getting used to a new food, maybe you have changed your brand name or you preferred to add new elements to your diet.

The second reason is constipation or constipation. If you do not see him defecate, it is necessary to give him some laxative, in addition to interrupting his normal diet and starting to give him hydrated food.

The last cause that can cause this symptom in a sick fish is anemia caused by intestinal parasites. If you notice that your fish is thin and does not eat, it will be best to remove it from the pond and transfer it to a fish tank that has constantly oxygenated water. In the new container, apply a treatment with tripaflavin (acriflavin) in the dose of 1 drop for every 3 liters of water for 3 days. Then repeat the process at the dose of 1 drop every 5 liters of water; during this time, you should not feed the fish.

  1. Your fish has white spots on the body

If the fish has white spots on some parts of the body or on its fins, it is probably due to some type of parasite. When the spots are similar to cotton specks, they are likely to be fungus.

In any case, a fish with white spots on the body should be treated with antibiotics and antiseptics that are added to the water. Treatments vary by species. Do not miss the following article: “White spot disease in fish”.

  1. Your fish gapes on the surface of the tank

When the fish approach the surface of the fish tank to catch their breath, with heavy breathing but accompanied by sluggish movements, you should check the low concentration of oxygen in the water.


It can also happen that the fish mouth and also have the gills swollen or reddened. This happens when there is a branchial infection due to the presence of a parasite.

If it just gasps, you should check the water conditions. Pay special attention in case you see many unicellular algae (they turn the water green). If so, add floating plants that help oxygenate the pond, as they will also help you eliminate single-celled algae. Another option is to use an anti-algae product.

If you notice any branchial infection apply a treatment of tripaflavin (acriflavin) in a dose of 1 drop for every 3 liters of water for 3 days. Then repeat the process with a dose of 1 drop every 5 liters of water.

This article is merely informative, at Guppy’s Aquarium Products we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

Contact us if you want more information about aquarium products!