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Is Your Goldfish Sitting at the Bottom of the Tank? 7 Main Causes

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By Lindsey Stanton

Sick goldfish lying

You look in your tank and think, “Something’s just not right with my fish…it just lays around.”

It’s true: Most goldfish (if they are healthy) will be swimming all over the place. So sitting at the bottom of the tank or in the corner lethargically is usually an indication that your fish isn’t feeling well.

But good news: Not always. Determining what’s wrong can help you get your fish back to normal (if needed).

Here’s the top 7 causes of bottom sitting in goldfish—and what you can do about it.aquarium plant divider

The 7 Main Causes of a Goldfish Sitting on the Bottom

1. Poor water quality

Credit: Madhourse, Shutterstock

Water quality is really the first thing to check when you notice your fish resting at the bottom. Is the tank newly set up? If you didn’t cycle it first, you may be dealing with high ammonia or nitrites. Both of these can cause the fish to feel bad.

When the fish feels bad from either of these, it may sink to the bottom and doesn’t look so hot. Ammonia & nitrites are both toxic to fish.

How to tell if your water has them? Simple…

Test the water.

You can use a simple dip strip kit or get fancy and use the liquid kind, either one works.

Look: ANY amount of ammonia or nitrites can cause this behavior. Now, what do you do to fix it? If you have ammonia or nitrite in your water, the first thing to do is perform a large water change.

You may notice your fish perks up after a couple of hours. This is because you’ve diluted the chemical in the water that’s making them feel lousy.

But don’t be fooled…in another day or so, it can come right back, especially in an uncycled aquarium. So, you will need to keep a close eye on the water via daily tests and water changes as needed to keep the fish healthy.

If you want to prevent high ammonia and nitrites when you add new fish, one option is to cycle the tank first before you get fish (if it’s too late now, maybe just log that away for next time, okay?)

So: Are your ammonia and nitrite levels fine?

If yes, let’s look at another possibility….

2. Parasites

sick gold fish_Suphakornx_shutterstock
Credit: Suphakronx, Shutterstock

This is another biggie. As stated before, fish that are feeling poorly often bottom sit. In many cases, this is actually due to a heavy parasite load that is making the fish feel just plain exhausted.

Several parasites that prey on goldfish chew away on the fish or even suck the fish’s blood. The worst part? You usually can’t see ’em. 

Flukes are a major cause of bottom sitting, especially in the first few months of owning your fish. Heavy loads make the fish feel so drained they don’t have much energy. These fish will often start swimming normally if you disturb them.

A dirty little secret? MOST pet store fish come to you flukey. If you suspect your lethargic fish has flukes, it’s important to treat quickly so you can turn things around. Untreated, heavy fluke infestations can be fatal. (Mainly because of the secondary bacterial infections they can cause.)

You can read more about diagnosing & treating flukes here: How to Treat Goldfish Flukes

Other parasites besides flukes could also be the cause, though I would say not as common.

If your fish has internal parasites, those could be leading to a loss of body mass of the fish which affects swimming ability and therefore water orientation. After ruling out water quality, performing a mucous scrape of the fish is a great way to identify parasites.

That said: If you don’t want to do that, you can usually proceed to just treat for parasites with a broad spectrum treatment like that mentioned in the fluke article, but I’d recommend you rule out other causes first.

If you think your goldfish may have a parasite but you aren’t sure which one, you should check out our best-selling book The Truth About Goldfish, on Amazon.

The Truth About Goldfish New Edition

It provides visuals of each possible ailment so you can diagnose accurately and start treating your pet ASAP so you can save your fish and keep them healthy.

3. Other diseases

bloated dropsy goldfish
Image Credit: Wari_Nuchczy, Shutterstock

Not all fish that sit at the bottom will have poor water quality or parasites as the root cause of their behavior. Internal diseases can cause a fish to do this as well.

Primarily thinking of internal bacterial infections here, which cause damage to the fish’s organs. Fish that show signs of dropsy or an emaciated belly may be suffering from internal bacterial infections causing it to feel bad and hug that substrate. Fish TB is one main one.

Internal bacterial infections can be pretty serious and fish may or may not recover with medication, depending on the cause.

4. Stress

Image Credit: BannokStock359, Shutterstock

Now, this generally is a less sinister problem but can be pretty common as well. Fish that have recently been shipped have been through a lot of stress—as have fish that have recently been introduced to your aquarium after taking them home from the pet store.

Sometimes it takes a few days for fish to adjust to their new surroundings. The cure for this one is to keep the lights off for a bit and give them time.

Now let’s talk about…

5. Long Fins & Body Modifications

Image Credit: Darko Cvetanoski, Shutterstock

I’ll let you in on a secret not a lot of people know about or understand. But fish that have long fins can end up spending a lot of time at the bottom because fins weigh them down. Generally, the older the fish gets the longer the fins get. So, the more time they feel like being lazy.

Fancy goldfish have had some pretty crazy things done to them to make them unique. And while this might look neat, things like big heavy eye sacks or big long fins or even too short of a body can disrupt the fish’s normal swimming patterns.

6. Constipation

sick fish
Credit: Andrii Oleksiienko, Shutterstock

Sometimes constipated fish will sink down. Once they get their system cleared out, they will return to normal.

Feeding peas may or may not help, but cutting back on the processed foods and feeding a more balanced diet usually does.

7. Swim bladder issue

A damaged swim bladder from a birth defect, injury or infection can cause the fish to loose their buoyancy. This usually makes them sink like a rock and even skuttle along the bottom when they try to swim.

Unfortunately, there isn’t much you can do for this problem, though some try flotation devices. Personally, I typically advise against them as they can cause injury to the outside of the fish.

Bonus Reason #1: Sleeping

Sometimes at night goldfish may sleep at the bottom like this but return to normal position during the day.

Bonus Reason #2: Eggs

A fish laden with eggs may spend more time at the bottom. If the goldfish is egg-bound, this can increase the chances for this behavior and the fish may need professional treatment.aquarium plant divider


Finding the cause of your goldfish bottom sitting may not always be easy, but once you do it can give you much more peace of mind.

So, now I want to hear from you. Have you ever struggled with your problem? What did you do to fix it?

Featured Image Credit: dien, Shutterstock

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