My wife got a goldfish from our pre-school. It came in a "fishbowl" the size of a large coffee cup and a tiny ziplock with fish food. It was severely stressed: fins clamped at his side, sunken belly, gulping bubbles at the top of the tank, flashing, drifting sideways, etc.

I had a used 3 gallon fish tank, but had no time to set up or cycle. So, I put the "fish-cup" in the center of the empty tank and over the period of days, added maybe 4-6 oz per hour of sink water to the fish-cup (I have a RO filter) until the tank water level exceeded the "fish-cup" and he could escape into the tank.

He did experience some shock (lethargy), but the flashing and side-drifting stopped. I kept adding RO water and removed and replaced the majority of the water almost daily.

Two days ago I started running the filter for about 4 hours during the day (on a timer). He's not happy about the water-current, but he is alive. He explores (I think he's looking for a way out) and hides in his cave when people are around. He's eating, resting, actively swimming. No flashing, no lethargy. His major stress comes from me exchanging water. He freaks out, but the water needs changing. Right?

I was going to start the kids with aquatic plants then eventually add ghost shrimp. Maybe a betta for Christmas. For all the prior neglect, this goldfish is in much better shape now. I know the tank is too small for the goldfish. I feed him twice daily. I exchange about a half-gallon of the water daily with a pinch of baking soda to offset acidity. But I am not going to do much more. I might add a plant, but I worry anything new might stress him. I've had him for a week now and he seems ok.

I've never had a goldfish before, so I don't know how they act. He seems to pace the tank like a caged tiger. Back and forth, up and down, front and back. After I add fish food, he waits... then stalks like a deep-water shark zipping up from the bottom and attacking at the surface. Is all of this "goldfish behavior" and him really needing a huge tank? Am I doing enough for his survival? If he lives a year, I might reconsider getting set up with a much larger tank. I just want to know if I'm giving him a sufficient minimum to survive.

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    The question contains a lot of details, but the summary is simply that you know what you're doing and that it's wrong. Your question goes beyond and asks for speculation about the survival change. If you have any change to give him away for free to anyone you know or a store, even the stress of the transport there would be a better than another week in such conditions. May 18, 2018 at 20:30
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    I appreciate the ideas. The fish is much happier now. He doesn't hide with water changes and he likes swimming against the filter current... He has a sweet spot in the middle of the tank where the "current" is strong and races in place like a hamster on his wheel. When he's tired he goes to his cave and rests. Otherwise, he patiently forages around his tank. I am in "do no harm" mode and if I can find a better home, I will. I won't take him to petsmart or walmart, that would end him. I'm just hoping freecycle has a post for a larger tank.
    – C.J.
    May 23, 2018 at 10:50
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    a filter needs to run 24/7 365 or it will not work,you can stop the filter while you change the water but only for a short time,3 hours is max after this the bacteria might start to die. Jul 12, 2018 at 4:34

2 Answers 2


You are trying to do well by the goldfish. But 3 gallons is still very small for a fish.

Your best steps now would be to get more information about fishes and aquaria. While the bigger the aquarium the better they are for fish, they also become expensive. So find out if this is a thing you want to put your money into.

Do you want to take care of fishes for the next 10 years? If not, find some one who provides the right care for this goldfish. If you do want to take care of fish, again, please read up on aquarium keeping. It will answer a lot of questions.

Cold water plants will be helpful for your gold fish.

Don't mix warm water species with cold ones. Beta's and shrimp have no place in the same aquarium as a gold fish.

  • My kids (ages 2 and 4) will be the caretakers over time, so I think as they're more invested, my wife will be. I am teaching them slowly: don't "scare" the fish, don't tap the tank, fish like to be happy, and his home is a little too small now... they're fascinated. I'm doing the best I can to keep our new pet happy, and he really seems much better: interactive, foraging, playful in the space he has. He arrived in very bad shape, so from a "start of the project" perspective I think I'm on the right track. But I wholeheartedly agree: bigger tank/better ecosystem are the next few steps.
    – C.J.
    May 23, 2018 at 11:00

Update if you're interested: A week ago I found a 20 gallon tank at a thrift store. The kids (and fish) are thrilled. For days now the fish has been foraging excitedly around all the new things in the larger tank (i.e. playing in his new playground). His basic survival in the small tank had depended on daily vacuuming while swapping out a gallon of water, and paying close attention to his mood (jumpy vs. lethargic). If something wasn't right with him, the variables were adjusted (food variety, fresh water, removing substrate, changing filter-timing). This kept him alive, and he was basically ok. But the real solution was a bigger tank. Normal goldfish behavior is constant exploration and foraging in and around everything. They inspect new things and are curious. If they're not doing that, they're either sleeping or something is wrong. Now that I know what to look for, I have never seen a happier fish. Thank you again to all who took an interest.

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    you need to run the filter 24/7 NOT on a timer. Jul 12, 2018 at 9:38
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    You need to read a lot about fish-care... And you need to know what is the function of the filter in the aquarium.
    – Gawey
    Jul 12, 2018 at 13:08

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