What Does Fish Poop Look Like? Here’s Why It’s Important to Know

Fish poop, like any other kind of poop, can vary in color, shape, and consistency.

It’s important to be aware of what fish poop normally looks like as any abnormalities can often be an indicator of a health problem with the fish.

So, what does fish poop look like? Fish poop is normally round, less-elongated, and sometimes strings. It should be of solid consistency and its color should match the color of the food that the fish are feeding on. If you notice any change in the appearance of fish poop, it can be a symptom of an infection, constipation, or overfeeding so it’s best to contact a professional to prescribe the right treatment.

Keep reading to learn more about how fish poop, the properties of fish poop, and how it can indicate the fish’s well-being.

What Is the Scientific Name of Fish Poop?

fish pooping to show what does fish poop look like

Scientifically, fish poop is known as detritus.

The word detritus refers to the dead particles of the organic materials that animals eat. This includes fragments of dead organic bodies and fecal particles.

This mixture of dead organic materials is dissolved in the fish’s digestive system then it’s excreted out of the body as poop where it decomposes by microorganisms to recycle the nutrients.

How Do Fish Poop?

Many often wonder how fish poop since there’s no visible opening apart from their mouth which actually led some to believe that fish poop out of their mouth.

But the truth is that fish excrete their fecal waste through a small opening known as the anus which is located at the end of the alimentary canal behind the fish’s rear fin. They also get rid of some kinds of waste through their gills and skin

How Often Do Fish Poop?

Fish poop as often as they need to, or whenever there is an urgency to eliminate waste from their system.

If the fish are fed the same quantities of food on a regular basis, they will poop at least once every 48 hours and they will maintain that frequency as long as their feeding schedule doesn’t change.

When the fish are not fed on a regular basis or if they’re starved, they will poop less frequently and might not poop at all for up to 4 days.

Fish might also take longer to poop if they’re overfed as their digestive system will become too jammed with undigested food and they can only poop when digestion is completed. It can take several days for them to finish digesting depending on how complex the food is.

Where Does Fish Poop Go?

When wild fish poop in the water, the poop will float through the current then settle on the bottom before it starts to slowly dissolve in the water. Undissolved parts will go deeper into the water and gradually break up into smaller pieces before getting decomposed by microorganisms.

Meanwhile, in an aquarium, the poop will mix with aquarium sand or pebbles and will soon dissolve in water. Undissolved parts will not completely vanish, so it’s recommended to regularly change the water to avoid messing up your aquarium.

Properties of Fish Poop

Fish poop can vary in color, shape, texture, size, and odor depending on the fish’s feeding behavior and health.

It’s important to know what fish poop would normally look like to be able to recognize any abnormalities that would indicate that there’s something wrong with the fish’s well-being.

Let’s break down all the properties of fish poop:

Color of Fish Poop

The normal color of fish poop usually ranges from brown to dark brown.

It can also depend on the color of the food that fish eats. That is because poop consists of waste products being expelled from the body and these waste products contain remains of undigested food particles.

For example, if the fish’s diet mainly consists of plants, their poop color will be green while if they eat flakes or certain worms, their poop color will be red.

Shape and Texture of Fish Poop

The normal shape of fish poop is more circular and less elongated. However, the shape might change depending on the fish’s diet and health.

For example, if the fish are overfed, the shape of the poop will become more elongated while in case of infection, it will become both round and stringy.

When it comes to the texture of the poop, it’s normally solid but it can be slimy and sticky depending on the fish’s health.

Size of Fish Poop

While it seems impossible, scientists were able to do some research to study the normal size of fish poop from different fish species.

According to research, it was discovered that fish poops are almost always the same in width which ranges from 0.6mm to 1.5mm. The length of the poop on the other hand varies according to the fish’s diet and health.

Smell of Fish Poop

Like any kind of poop, fish poop would typically have a distinctive unpleasant smell.

In open waters, this kind of smell wouldn’t be very noticeable and it would go away quickly since the poop would dissolve in the water.

In still water, on the other hand, the smell can be much stronger especially in a closed aquarium as it can build up over time. So, it’s very important to frequently change the water in your aquarium to keep the water clean and free of any unpleasant smells.

Can Fish Poop Indicate the Fish’s Health?

Similar to human beings, the color and consistency of fish poop can indicate a lot about their health. 

So, the best way to recognize issues in the fish’s health is to observe their poop appearance as well as frequency. This will allow you to address and treat any symptoms early as fish are sensitive creatures and if they’re not treated on time they will stop eating and die within a few days

So, let’s take a look at what some abnormal fish poop appearance could indicate about the fish’s health:

Black Fish Poop

In humans, black poop usually indicates an increase in iron levels in their diet or it could be a sign of internal bleeding. With fish, however, black poop can be a symptom of constipation or a kind of parasitic infection in their digestive tract.

This could happen due to a change in the fish’s diet. If the fish stop eating, it’s recommended not to try any kind of medication by yourself and to consult a vet as soon as possible.

Related: check out this guide to why do Trout turn black here.

Brown Stringy Fish Poop

Long stringy fish poop is a clear sign of constipation. This kind of poop will not float immediately after it’s expelled as it will remain hanging from the fish’s body and trailing behind them.

The normal color of poop ranges from brown to dark brown but if the color keeps getting darker and darker, this could also be a sign of constipation. 

Constipation could happen due to a poor diet or an anal inflammation and it could be deadly to the fish if left untreated.

White Fish Poop

White fish poop often indicates the presence of bacteria in the fish’s digestive tract. You can make sure by checking the texture and shape as it’s usually stringy and lumpy.

It can also be caused by malnutrition as the fish wouldn’t be getting enough nutrients.

If the white poop is too pale or even translucent, this could be a sign of underfeeding your fish or that there are not enough nutrients in their diet. At this point, it’s not actually poop that the fish are expelling, but rather the mucus coating in their digestive tract.

Air Bubbles in Fish Poop

The presence of air bubbles in fish poop means that the fish are not getting enough oxygen as they will be gasping in for more air.

This can happen because the water is too warm or because your tank is overstocked.

How to Deal with Irregular Fish Pooping?

To maintain regular pooping behavior in fish, you need to maintain healthy eating behavior and metabolism.

Here are some tips you can follow to ensure that you’re properly feeding your fish:

  • Enhance eating conditions in the tank by keeping the water temperature comfortable. It’s recommended to keep the water temperature between 76 and 81°F because colder temperatures can slow down the fish’s metabolism.
  • Make sure the water in the tank is well oxygenated and clean. Make sure to remove any food remains and change the water in the tank regularly.
  • Try to feed your fish once in the early morning and once at dusk. This will help your fish get used to a regular feeding schedule and anticipate their next meal.
  • Don’t feed the fish more than twice a day as they won’t be able to eat all of the food and it will begin to decompose in the tank which could kill the fish.
  • Make sure the food you’re feeding the fish is not larger than their mouth so they can easily eat and digest it.
  • Try to make your fish fast once a week as this can improve their digestion and help treat constipation.

Related Questions

Do Fish Poop Out of Their Mouth?

Fish do not poop out of their mouth. They poop out through their anus that’s located behind their rear fin. It might appear sometimes that fish are expelling poop out of their mouth but it’s mostly food particles that fish try to soften by spitting them out and eating them again.

How to Make Fish Poop?

The best way to make fish poop is to change their diet pattern for a few days. You need to include fiber-rich products as they are the most effective in treating cases of constipation in fish. If changing the diet doesn’t work, it’s recommended to seek a vet to prescribe some laxatives.

Why Does Fish Poop Have Multiple Strands?

Fish poop might have multiple strands if the fish are suffering from Carnallanus worms. The strands will be hanging from the fish’s body and they will be more noticeable if the color of the poop is red or brown. It’s recommended to consult a vet as soon as possible to get the right treatment for this condition.

Will Fish Eat Their Own Poop?

Fish will generally not eat their own poop. They sometimes consume poop by accident but you’ll notice that they will spit it out again. If you do notice that your fish are eating their own poop, this could mean that the fish are very hungry or that the water in the tank needs to be changed as soon as possible.

Can You Use Fish Poop as a Fertilizer?

You can use fish poop as fertilizer along with the water in the tank. Fish poop can help increase the fertility of the soil because it contains ammonia that decomposes into nitrates by the bacteria in the water. The nitrate will be absorbed by the plants in the soil and enhance plant growth. So, it’s a good idea to recycle fish poop and tank water to keep balance in the ecosystem.

Helpful Resources 

Why Scientists Just Ran Numbers on All The Fish Poop in The World’s Oceans

Stringy White Fish Poop

Find Fish Faster Anywhere, Anytime

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