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Why Do Goldfish Eat Their Own Poop?

Goldfish are interesting fish and will do random, weird things in a captive environment. Goldfish are heavy eaters and heavy poopers- there is no denying that. They come in many different colors, shapes and sizes and they are always searching for food. You might say that Goldfish are ravenous eaters.

Goldfish are scavengers and that is why they eat their own poop. It is not because goldfish desire to eat poop. They are foraging for food and when poop is found, the goldfish eat it thinking it is a food source. Goldfish are quick at eating anything small enough to fit in their mouths, especially if they are already hungry. 

Goldfish eat a lot if you let them. The way goldfish scour around the tank looking for food is almost like they do it with their eyes closed because anything that will fit in their mouths will end up in their stomachs. Unless, of course, your pet goldfish are properly cared for. In this article, I will talk about proper care as well as why goldfish eat their own poop.

Is It Normal for Fish to Eat Their Own Poop?

Yes, usually fish eat their own poop because they are either lacking food in the tank or simply because it has been a couple of hours and they are starting to get hungry. Goldfish and koi are notorious for eating poop while trying to find food. They are not the only fish that will do this, however.

Is Goldfish Poop Toxic or Bad for Them?

Fish poop contains bacteria and organisms just like human excrement. If a large amount were ingested for a long period of time, a fish could get sick.

My uneducated guess, however, is that goldfish will not experience a toxic effect if they happen to ingest poop on occasion.

Is poop bad for goldfish? I would have to say not necessarily bad unless you consider containing zero nutrition bad. In that case, then yes, goldfish poop is bad for them.

You will probably find that most goldfish will end up spitting the poop back out once they realize it is not food.

goldfish eating their poop

How to Stop Goldfish from Eating their Poop

The first thing to know is you will not be able to stop goldfish from eating their poop entirely. It is their nature to poke around looking for food and they devour just about anything that happens to be there and floats into their mouth.

You can, however, minimize how much poop a goldfish will consume by doing a few simple things and that is what I will go over now.


  • Keeping up to date on tank maintenance is an important part of maintaining the proper water parameters as well as keeping the tank somewhat poop free.


  • By vacuuming the substrate, you will be removing decaying plants, food, and fish poop. Since goldfish are big poopers, you might want to do water changes a bit more often. The only problem with that is if you remove too much liquid, you risk messing up the water parameters. My recommendation would be to take no more than 10% of the tank’s water every week.


  • Minimizing the amount of food you feed your goldfish can help reduce the amount of waste. It is amazing how little food your fish actually needs to survive. I used to over feed every single time I fed my fish without knowing it. Once I became more experienced in the hobby, I realized this was happening and started cutting back the quantity of food I gave at each feeding.
      • You will find if you do this, your tank water parameters will improve, the tank is much easier to keep clean, the fish become much more active and you save yourself a small amount of money. The only thing I would say to watch out for is that all fish are getting some food each feeding and that none of the fish are starting to become aggressive. Just adjust the quantities accordingly.


  • Having a power head pointed just above the surface of the substrate and an oversized filter on the other side of the tank can help clean up anything light enough to be moved along in the water like excess food or poop before it gets caught in the substrate.

One more suggestion is if you take my advice and use a powerhead to move objects in the water towards a filter, why not minimize the amount of substrate in your tank? The less substrate you have, the less likely for any floating debris such as poop, excess food, or pieces of live plants to get caught in the material.

Another option is to use sand instead of gravel as substrate. With sand, you will find the debris floating in the tank will not penetrate but rather sit on the top. This makes it easier to remove organic matter from the aquarium.


To wrap this article up, I want to reiterate that if you see your goldfish eating poop, you probably don’t have to worry about the fish.

What you should be concerned with is how you can get rid of the fish poop as quickly as possible – so this gross activity does not happen as often.

I have given some solid ideas on how you can keep feces in the fish tank to a minimum and I hope you take my advice and implement them. A clear tank is a beautiful sight to behold so make sure you are keeping yours as clean as possible.

Thanks for reading and good luck tackling this fish tank issue.

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