I have a tank with four 1.5" Shubunkins, which I've had for one month. There are no other fish. It is a glass-bottom tank with no substrate (for easy cleaning), and has many floating plants for them to hide in. The tank is equipped with just an AquaClear filter and an auto-feeder.

Whenever someone approaches the tank, all of the fish run into the plants, and won't come out. They only swim around when they don't see anyone nearby. I've never seen any other fish behave this way, except maybe catfish.

Why might the fish always be scared? Is that a sign there is something wrong with the tank?

  • 1
    What are you levels of Ammonia, Nitrite and Nitrate? This may point to potential issues. How long has the tank been set up for?
    – Henders
    Jan 26, 2018 at 14:02
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    The tank has been setup for about 6 months. It had other fish, but I donated them to a school. I will buy a test kit and check. I've done frequent, huge water changes, so I thought that was not an issue.
    – Village
    Jan 26, 2018 at 21:34
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    i am not sure you need to worry about this,sometimes when one walks up to a tank the vibrations get transfered to the tank via the floor you walk on.what happens if you stand still for some time do the fish stay scared? Jan 27, 2018 at 11:32
  • A clipon filter is likely inadequate for 4 fancy goldfish. Also don't put tanks near doors and frequent traffic. Mar 3, 2018 at 8:36
  • "is something wrong with the tank" - yes, there is. There is no substrate (so decomposing matter cannot accumulate in order to grow the beneficial bacteria). Also, i guess that there is too much cleaning - that is why you do not even have a substrate, in the first place. Also, the tank is probably not cycled either, if you have it for only one month, with no substrate and a lot of cleaning.
    – virolino
    Dec 13, 2022 at 7:27

2 Answers 2


I had this same issue with my Danios, and it confused me because Danios are usually all about coming up and trying to get your attention when they see you.

then I realized, the autofeeder was the problem. they weren't associating the big scary noisy thing outside the tank (me) with a sudden abundance of delicious foods, but Instinct was telling them that anything that big is probably dangerous. I'm pretty sure goldfish have similar instincts.

Maybe I'm off base in my theory, but i started feeding them by hand again and in no time they were back at the front of the tank being the little beggars that they are, whenever you walk by. I still use my autofeeder for a daphnia culture that I've had going for a while.

My advice is to try feeding them by hand for a week or so, see how it goes! As others here have said, it never hurts to check your water parameters, either.


I understand that the tank does not have any substrate for easier clean up, what you have to understand is that goldfish don't have stomachs like other fish do, so what goes in quickly goes out, this is why goldfish are considered dirty fish that most put in ponds and call it a day. Like @Henders asked about your levels, they wouldn't have anything to do with your fish being scared BUT you should keep in mind that with no beneficial bacteria to grow in your tank, your levels can quickly change due to the fact of having goldfish.

Your question has to do with the scared factor of your fish which I will answer along with some other tips that can help you on your journey.

Fish have confidence levels just like anybody else, if you give your fish what they need, they will feel no need to hide. In a normal setting whether it be a store, pond, lake or whatever, there is substrate. You need the substrate because it holds on to their waste which creates what is called the Nitrogen Cycle, in a short version, you feed your fish, the waste created by fish (poop) is then turned into Ammonia, that ammonia is then turned into Nitrites and then into Nitrate which is then removed when you do a water change. Without any substrate, I'm assuming you do weekly or daily water changes on your tank which blocks the cycle from happening. Ammonia is the #1 killer of fish, if it can't change in to the lesser toxic version of it which is Nitrite then Nitrate, your tank is just a bowl of toxins that shouldn't just be removed by water changes. If you add substrate, your tank will go through the cycles as it should keeping your levels healthy and your tank clean.

By the way if you're concerned about your tank being cloudy, its because of the cycle. If the nitrogen cycle does not happen, your tank will become cloudy going through a daily or weekly syndrome called New Tank Syndrome, it happens because ammonia, nitrite, and nitrate levels are high. The only way to fix it is to leave the tank alone to fix it self and if it's really bad do only 10% water changes.

You should only be changing your water every month doing 25% changes or weekly doing 10%.

Besides the substrate helping with that, you need anchored plants and a lot of decorations to boost your fish's confidence and not hide anymore. Just because you have plants floating does not mean that it's enough.


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