Decoding goldfish behavior

If you keep pet goldfish, you have almost certainly spent many hours watching them go about their daily lives, interacting with their surroundings and each other, and doing all of the normal things that goldfish do!

But have you ever watched your goldfish swimming around and wondered exactly why they are doing what they are doing, or what their behavior means? Many of us have!

Goldfish are generally thought of as being fairly simple creatures, and the different behaviors that they exhibit are not difficult to interpret, if you know what you are looking for. Read on to learn about how to decode some of the most common pet goldfish behaviors.

Understand how your goldfish behaves

Socialization and taming

Goldfish are fairly social fish, and are also credited with the ability to learn by association. Unless they are in competition with each other for food, even goldfish of different sizes and ages will rarely behave aggressively towards each other, and will come to recognize the other fish in their tank over time.

Goldfish also become used to the presence of the people that feed them and that they see every day. They will soon learn when feeding time is and that, if someone approaches, they might soon be fed! Goldfish will often come to the top of the tank when someone approaches or follow the progress of a hand moving on the other side of the glass.


Goldfish love to dig about in the substrate of the tank! This is normal goldfish behavior and one that you will be able to observe quite often. There are elements of both foraging for food scraps and making their mark on their environment involved with this activity, and as grazing fish, goldfish do like to constantly have something to nibble on!

Goldfish will also often eat the plants within their tank, and this behavior can be viewed in the same way as any other grazing animal, such as a horse or a cow, whose metabolism is constantly in motion.


Goldfish are not always among the fastest moving fish, but occasionally they will show quite a turn of speed! If your goldfish are chasing each other around the tank, this is sometimes the lead up to mating and generally not cause for concern.

However, if your tank is overcrowded or your fish are in competition over food, your goldfish may become stressed and chase each other off in competition for resources.

Hovering at the tank’s surface

Goldfish tend to use the full depth of their tanks from top to bottom, unlike some species that generally show a marked preference for a certain area of the tank. However, goldfish will congregate near to the top of the tank if they are expecting food or if the oxygen levels in the tank are low.

If your fish are gulping air at the surface of the tank or are regularly breaking the surface of the water, check your water quality and aeration for any problems.

19 thoughts on “Decoding goldfish behavior”

  1. My big fan tail fish is benign chased by 3/4 smaller sized fan tail fish for most of the day today and the day before and not sure why. It’s like there going for the bottom of the tail on my fish and the tubing up and piken the sides of it. I have 15 fish and its only 3/4 that do it rest of them dont bother. Any ideas to why there doing it would be great.

    • Hi Kassandra – thanks for your message. Are you saying that you have 15 goldfish? Or goldfish with other types of fish too? Are they in a pond?

      If your fish aren’t in a pond or an extremely large tank, it’s possible that over-stocking (likely leading to poor water quality) could be a factor in your fish’s behaviour.

      • Hi all, turns out my goldfish was attack by this thick white layer. So quick that thing grow it was all over its body, (pictorial fin, tails, head, mouth.) I just placed him in a salt bath and melafix for 24h now, the body seem clearer without that white layer anymore, but it seem passive with little move, rest at the bottom of the tank . It wont eat anything either. What should i do ….am soo saddd

  2. My daughter won 2 goldfish at a fair a year and a half ago. We had them in a 1 1/2 gallon cylinder tank, but a week ago moved them to a 10-gallon with a more powerful filter (creates more current in the water) and led light. They hide at the back bottom corner anytime a light is on (the light in their tank or the light in the room) or if they notice one of us near the tank. They also are not eating nearly as much as they did in the old tank. A friend who is really into fish keeping came over and set up the new tank for us and she is stumped. We’ve checked pH, ammonia, nitrite, and nitrate levels and done a 1/4 water change. Any thoughts?

    • Hi Ellen. Are there other objects such as plants or ornaments in the tank? While you don’t want to add too many – every object takes up valuable water space, especially in a 10 gallon – goldfish do like to have somewhere to hide rather than being out in the open all the time.

  3. My goldfish gets so excited when she sees me. Its almost as if she wants me to pick her up and cuddle her and its EVERY time I’m working on the surface where her tank is. I feel I have to get out of her sight to let her rest. Is this normal?

    • Hi Cheryl, thanks for your comment. This does sound totally normal! Goldfish can get to recognise people and they definitely associate people with being fed. Perhaps your goldfish is hoping for some food every time she sees you?

  4. I have a small garden pond which had two goldfish. One was taken a few weeks ago.bive just replaced with a new goldfish and the original one is chasing it everywhere. No aggression, just shadowing. Is this normal?

  5. Hi, we have 4 x goldfish and today noticed that 3 are chasing 1 fit a good portion of the day, I suspect he is a she and possibly trying to mate,
    Question: is mating during a particular time of year and what are the chances of this fish become pregnant and producing fish eggs which new born surviving?


  6. I have a short video of my goldfish making noises when he sees me in the room and wants food. How may I post or send it to you?

  7. One of my goldfish has been nibbling another underneath its tail. Could he be eating waste matter from the fish?

  8. Hello!
    Goldfish keeper of 1year now.
    I have a question about my Fancy goldfish Jaws.
    We recently moved 3 fancy goldfish over from a 30Gal to a 75Gal (yes I know it was a little squishy, that’s why we got a bigger tank). It’s about 3weeks now and Jaws is obsessed with swimming to the top left corner surface of the tank where my sponge filter bubbles come up from, where the pathos plants are and is close to the filter output.
    He literally just swims towards it for HOURS. He doesn’t eat the pathos, just swims towards the bubbles and towards the water output from the filter.
    He’s never done this in the 30Gal, the other two goldfish don’t do this, only him. His dorsal fin is out of the water when he does this and his face is almost breaking the surface. He does this after water changes and water parameters are good.
    I think my fish is broken…. All feedback welcome and appreciated.

  9. I have a big 20cm comet and a 15cm black moor in a 200L tank. There’s only two small orandas in there with them. These two aggressively chase And nudge each other every evening. But there’s no nipping or biting. It can be quite stressful to watch as they get splashy sometimes. I worry they’re stressing each other out but they seem fine afterwards and it’s been happening for a while now. Should I be concerned? I hope they’re just playing.

  10. Hi… I recently purchased my two large goldfish and they were extremely playful with each. I noticed recently only during feeding time the male goldfish get a little aggressive and keeps knocking the female one. What should I do???

    • Hi Ronell, thanks for the comment. As long as the male goldfish isn’t being aggressive all the time, or knocking hard enough to cause injury, then this doesn’t sound too concerning. Though obviously it would be good to stop all aggression if possible.

      If it’s only happening at feeding time and they’re fighting over food then have you tried adding food at opposite ends of the tank to see whether you can encourage them to eat separately?

  11. Hi please help!! I just got this goldfish about 3 weeks ago and everything was great but all the sudden he seems not him self, just sitting in the corner or at the bottom laying on the gravel he has a fee white spots on his fins that have gotten worse but i have treated for ich and fin rot because i cant tell for sure what it is, he also just kind of floats lazily like hes bored but something is definitely wrong please some one help me! I dont want to lose him! All water readings are great no ammonia no nitrite no nitrate and ph is a little high at 8.0 but always has been so what should i do? He is also flashing occasionally


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