Today I went to the pet shop and got a goldfish. My tank is 20 litres, and the goldfish is pretty small. When I first got the fish, it was gasping and eating the bubbles in the bag. I thought this was normal. At home I let it acclimate and everything then I put it in the tank.

It is swimming fine and not rapidly breathing but it goes to my air stone and filter and eats the bubbles. I don’t know why this is happening because I have enough oxygen in there and I know that.

I have an air stone and filter. I think it might be because one of the suction cups that was holding up the filter got loose and the goldfish keeps on eating the stuff on that so maybe it needs more air to supplement the food it’s eating or something like that. I have no idea.

Is it maybe just because it is stressed and hasn’t got used to the place? Please help I don’t want him to die. He doesn’t go up to the surface too often though like maybe a few times every minute. Please help though

  • 1
    what are the readings of your watertest ammonia-nitrite-ph,for how long did you cycle your tank before you got the fish.you can read about how to cycle your tank here fishlore.com/NitrogenCycle.htm your tank is way to small for keeping goldfish.please edit the information into your question. Jan 6, 2020 at 10:38
  • I cycled my tank for a really long time. And last time I checked it (yesterday) the ammonia and everything was fine. Jan 6, 2020 at 22:15
  • Is it gasping at air at the surface or just eating bubbles?
    – Pam
    Jan 16, 2020 at 19:34

2 Answers 2


If your fish is gasping for air something is clearly wrong. It can be ammonia (this is a waste product from your fish urine and decomposing food and plant matter).

Ammonia will be broken down by bacteria and create nitrite, this and ammonia is toxic to fish and other life in your tank. You can read more about this in the article on fishlore.com.

The end product of bacterial metabolism of ammonia and nitrite is nitrate (plant food). This is not toxic, unless the concentration gets high. To keep the nitrate down, you need to change some water every week.

When your fish gets ill the first thing to do is to stop feeding to get the bioload down; you need to take water tests to find the cause of the problem, it is often ammonia or nitrite poisoning that is the root cause for fish getting ill.

Poor maintenance of a tank will often result in problems for your fish. You need to vacuum the gravel about twice a month, change about 20% of the water each week and clean the filter when you can see the flow is reduced (use water from your tank when you rinse the filter material). Do not clean more than half of the filter material each time you do this.

A tank of only 20 liters is too small for goldfish (and most other fish). You will need a tank of 60 liters or larger for one single goldfish. More information about this could be found in this article on thegoldfishtank.com.

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    I looked at that "the goldfish tank" site. It's all wrong. 80 degrees Fahrenheit is too hot for a goldfish tank. Goldfish like cold water. If the plecos like it, the goldfish don't. Don't let the temperature get over 70 degrees Fahrenheit. Goldfish can really stink up a tank. I had two fantails and they took a 100 gallon tank. You need to change more than 20% of the water. 60% is more like it. I don't want to be mean here, but you need to get the ammonia out of the water or the goldfish will get fin rot.
    – Peter
    Mar 24, 2020 at 20:28
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    @Peter please read this fishlore.com/NitrogenCycle.htm if the tank is properly cycled all of the ammonia is converted to nitrite and then converted to nitrate so one does only need to change about 20% of the water each week to keep the nitrate down.you are right goldfish is cold water fish and they need temparature around 15-20C to live a good life.i first started keeping fish in 1974 so i think i know a thing or two about keeping fish and how to maintain biological balance in fish tanks. Mar 24, 2020 at 21:48
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    Sure, there is that nitrogen thing. This 100 gallon tank was from a long,long,time ago. I got rid of it because my father made me .My point is,goldfish can really mess up a tank. Especially orandas.
    – Peter
    Mar 25, 2020 at 17:54
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    @Peter goldfish and other fish in the carp family do produce a lot of waste products so they should not be in a small tank at all,the best life for a goldfish is to live outside in a pond and they will get tame and come to you to get food and to get touched/stroked.here is a little video of my pond and fish youtube.com/watch?v=qNzl_KSJoss no goldfish but many koi and at the end my cat electra she died a short time after i filmed this video i miss her like crazy. Mar 26, 2020 at 9:22

Gasping for air can mean a few things. First you want to check all parameters. You already checked ammonia, nitrite and nitrate. Check pH, hardness and temperature. Gasping usually means the metabolism is in over drive (too hot, stressed) or there is an issue with the gills (not enough O2, irritation, infection, poor water quality). Eating bubbles is just a weird behavior in some fish and not recommended, try to prevent it and make sure you fish has plenty to eat but no left overs. Eating air bubbles can interfere with the swim bladder and force the fish to the surface.

Prevent your fish from getting stressed out, so don’t make water changes too fast. Rule out water quality as an issue. Next look for any irritation, infection or parasite on the gills. They could be swollen and red, tiny white dots, white cotton appearance, black tiny dots.

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