Aquarium Scuds: What Are They & What To Do About Them

If you’ve seen tiny shrimp-like creatures in your tank and didn’t put them there, don’t panic; they’re probably just aquarium scuds. Scuds are small invertebrates that are mostly found in freshwater ecosystems. While they have some benefits to aquarium inhabitants, when they form a colony, they can become hard to remove from your tank and dangerous to juvenile fish.

If you’re struggling to remove them from your tank, you’ve come to the right place. In this article, we’ll tell you more about these interesting creatures, what to do if you find them in your tank, and how to get rid of them if they are causing a menace.

Aquarium Scuds

Scuds are considered Amphipoda or freshwater amphipods. Because they are freshwater crustaceans, you’ll find that aquarium scuds will take over most freshwater ecosystems in their natural habitat.

You can find them almost anywhere. Freshwater scuds can be found in their natural habitats like swamps, lakes, freshwater streams, shallow rivers, and ponds. In a fish tank, they spend most of their time at the bottom or hiding in places like driftwood or substrate.

Because they reproduce at such a high rate, their population grows quickly in a fish tank making it harder to get rid of them once they start causing trouble.

What Do Aquarium Scuds Look Like? 

Scuds are small and grow to 3-8mm in length once they become adults. Because of their semi-transparent body, some scuds are brown, green, yellow, grey, and white. Females carrying eggs will often look orange in color. Unless they are in a colony, it can be hard to identify them because of how they blend into their environment.

aquarium scuds

Their bodies are divided into three groups. The head has two antennae pairs, a thorax with seven segments, and six on the abdomen. Scuds’ lifespan is between 1-2 years. But this is highly dependent on their living conditions and environment.

Aquarium scuds undergo nine different group cycles during their lives. It’s common to see them shredding every couple of days. Although they like cool temperatures, colder water than they are used to in their natural habitat can kill them.

How Do Scuds Get Into Your Fish Tank? 

Aquarium scuds can get into the fish tank through plants and other tank decorations like gravel and rocks. They mostly end up in tanks by accident. You won’t easily spot them in your tank because they’re so small until they have reproduced. That’s when you’ll start noticing them everywhere.

They could also enter the tank when introducing new fish or shrimp bought from your local fish store, so you always have to be on the lookout. Quarantining everything, including new fish and tank decorations, is the most effective way to prevent scuds from hitching a ride into your freshwater aquarium.

What Do Aquarium Scuds Eat? 

Aquarium scuds are omnivorous and will enjoy eating decaying plant matter, algae, and other waste products in the tank. They are classic scavengers.

scuds in aquarium

Generally, aquarium scuds are harmless. They mind their business, eat, and reproduce like other creatures in a freshwater aquarium. You should be careful, though, because, as you’ll find out below, a large scud population harms the plants in your freshwater aquarium.

If you can control their population, they can actually be a great addition to your tank because they eat algae.

Effects of Having Scuds in Your Aquarium Fish Tank 

There are benefits and drawbacks to having scuds in your aquarium. A few of them are fine, but when their population grows exponentially, these creatures can be harmful to other living creatures.

Keep reading to find out why:


Scuds are an ideal food source for fish. They reproduce fast, offering an endless supply of food, especially if you keep them in a separate tank. Fish love live food. Instead of always buying from your local fish store, which is expensive, you can consider breeding scuds.

Many fish keepers will breed scuds for this purpose. Who can blame them? If you have freshwater fish, you can freeze scuds and offer them to the fish to diversify their diet.

Fish Fry and Baby Shrimp

Scuds aren’t harmful to fish but can be dangerous to fish fry and shrimp. Scuds are opportunistic, and they will eat fish eggs when they get the chance. This isn’t good, especially if you’re breeding fish and have small fry in the tank.

If you’re considering breeding shrimp, putting them in one tank with scuds is not a good idea. Scuds and dwarf shrimp will compete for the tank’s available resources like food, living spaces, and oxygen. If you want your baby shrimps to grow healthy, they shouldn’t be in the same tank with aquarium scuds.

If you have a community tank, the larger fish are good at keeping the freshwater scuds at bay. Be careful, though, because larger fish are also capable of eating baby shrimp.


Scuds are very good at eating food that’s not theirs, including food meant for snails. Not only will they eat the snail’s food, but they can also be irritating to snails, causing them stress and even leading to their death.

The best solution is to separate the scuds from other fish or shrimp, or snails.

Aquarium Plants 

Although a few scuds aren’t harmful to plants, a large population of them could damage the plants in your freshwater tank. Scuds will eat live plants like mosses if you don’t provide an alternative food source.

scuds in fish tank

They’ll go for plant leaves and leave the stems unharmed. Plants that most fish keepers have found that aquarium scuds like to eat include: 

  • Java Mosses
  • Amazon sword
  • Hornwort
  • Anacharis
  • Dwarf Sagittarius
  • Java Fern
  • Totals rotundifolia

Softer plants are an easy target for scuds, so be cautious when choosing aquarium plants for your home aquarium. Some aquarium scuds also eat the plant’s roots, so don’t put anything past these creatures. This can lead to your plants rotting, and that’s not good for any animals in your fish tank.

The solution is to fill the tank with floating plants. These are more likely to survive a scud infestation and make it more attractive for fish to eat the scuds .


Fish need food to survive, so if scuds threaten that, they must be removed. As mentioned, scuds can start competing for food with other tank inhabitants, like shrimp and snails.

Scuds will also feed on leftover food, rotting leaves, decaying plants, and algae which will keep the tank clean by controlling the ammonia levels. But a sizeable scud population will also compete with the smaller fish for food.

The more these large colonies eat, the more waste they produce. This contributes to ammonia buildup in the tank and lowers the oxygen levels. Low oxygen levels aren’t good for fish and other living creatures in the tank.

All those aquarium scuds eating the leftover food will help reduce ammonia buildup in your fish tank. While this is good, it doesn’t outweigh the waste these colonies can leave behind after eating.

Tanks Appearance 

Every aquarist wants to have a good-looking tank. That’s why so much time and effort is spent decorating it with plants, driftwood, and rocks. While some fish keepers don’t mind having aquarium scuds in their tank, others feel scuds completely ruin the aquarium’s general appearance.

Are Aquarium Scuds Harmful? 

They can be, yes. As mentioned above, scuds can harm plants, fish eggs, and snails. While they can offer food to some fish, a large population generally harms your tank and its inhabitants.

Breeding Aquarium Scuds

As mentioned above, scuds have benefits and drawbacks, but any fishkeeper should consider them. It’s not surprising that some fish keepers want to breed these invertebrates when they can be such a reliable and easy source of food. If you have a scud tank, you won’t have to worry about controlling their population and protecting shrimps and fish fry.

If you’re one of those fish keepers, breeding aquarium scuds is possible with the right equipment and water temperatures.

How To Start a Scud Aquarium 

aquarium scuds

Whether you are an experienced or beginner fish keeper, you can breed scuds. Here’s how:

  • To start your scud tank, you’ll need a spacious tank of at least 3-5 gallons. 
  • Inside the tank, these creatures will need substrate because they are bottom dwellers and will need a place to hide and eat leftover food from. 
  • A scud tank won’t require heavy filtration because, unlike other marine creatures, they don’t produce a lot of waste. Sponge filters are the best option because you’ll still need to keep the tank clean, and these invertebrates love munching on algae found around filters.
  • You’ll have to add plenty of driftwood and tank decor like rocks because this provides plenty of hiding places and feeding spots for scuds.  
  • A planted tank is recommended for your aquarium scuds because they love to eat decaying plant matter. So the more you have, the better. Aquarium scuds will eat tank waste, so you won’t have to clean your tank as often as if they weren’t there.
  • Carry out 10 to 20% water changes to maintain the proper water parameters: 68 to 74°F and pH of 7 to 8.
  • You should feed freshwater aquarium scuds a couple of times per week but ensure not to overfeed them. Some great food options you can give scuds aside from plants include algae wafers and shrimp food. 

How Fast Do Scuds Reproduce? 

Scuds reproduce quickly; in three weeks your tank can be full of scuds. Female scuds can carry between 20 to 30 eggs, but bigger females can carry even more. After hatching, the young scuds can survive independently and usually measure 1 mm in length. Their fast reproduction rate provides you with an endless supply of live food for larger fish.

How To Get Rid of Aquarium Scuds

A scud infestation in your tank can be quite a problem for any fish keeper. It can damage the freshwater ecosystem for other freshwater creatures. But luckily, there are various methods you can use to get rid of scuds completely.

Methods to use to get rid of scuds from your tank:

Clean The Tank

Cleaning the tank is always good for your fish and other aquatic life in your home aquarium. While you can’t completely get rid of these scuds, you can control the population by continuously cleaning the aquarium and other tank decorations like plants, filters, and gravel. An intense tank cleaning is one of the best ways to remove the scuds effectively.

They love hiding under plants, so use cleaning agents that aren’t too strong. They love to feed on algae, so you should constantly clean the filter. Change the sponge filter media as well. You might also have to change the substrate to be on the safe side.

Please do not use bleach to clean the tank because it could have adverse effects on the tank’s plants.

Manually Remove Them From The Tank

One of the fastest ways of removing scuds from your tank is using traps to get them out. You can place the scud trap in different parts of the fish tank and wait for them to do their job. You can use zucchini to set up the scud trap and remove it once it’s caught plenty of scuds.

aquarium scud

This is one of the easiest and most effective ways to get them out without damaging other tank inhabitants. Scuds are fast, so don’t be surprised if they find a way to avoid the traps altogether.

You could also use the baiting process to remove scuds. All you have to do is place boiled foods like carrots. The scuds will make their way to the food giving you an easier way to snatch and remove them from the aquarium. This method is more likely to work if you turn the lights off.

Reduce The Oxygen Levels in The Tank

Like other aquatic creatures, reducing the oxygen levels and increasing the carbon dioxide levels in the tank will suffocate and kill the scuds. If you don’t also want to suffocate your fish and other living organisms, you’ll have to remove them from the tank to a new fish tank before using this method.

The temporary fish tank should have the required water parameters so as not to stress your freshwater fish. Increasing the carbon dioxide levels will take 1-2 hours to kill the scud population in your tank.

If you plan to return the fish and other creatures like shrimp to the main tank, check the oxygen levels and other water parameters first. The constant change in temperatures isn’t good for your fish’s health.

Introduce Bigger Fish Into The Tank

As mentioned above, aquarium scuds are a great option for fish food. But not just any fish. You need to add larger fish with a large enough appetite to take care of your scud infestation. There are numerous fish species who eat scuds; they include:

  • Cichlids
  • Loaches
  • Mollies
  • Killifish
  • Bettas
  • Pea puffers
  • Adult guppies
  • Tetras

From this list, it’s clear that most tropical fish will eat scuds. If the new tank inhabitants don’t have other food sources, they are more likely to eat scuds and help you reduce their population in the freshwater tank.

A downside to using this method to get rid of scuds is once they have established themselves in your tank, even using bigger fish may not be enough to get rid of them completely. Or it may take too long and cause too much damage. It’s also more challenging to get rid of the scuds hiding in plants and under the driftwood. 

Reduce The Water Temperatures 

Scuds don’t like freezing temperatures. So one way to quickly get rid of them is by reducing the tank’s temperature too close to the freezing point, which they can’t survive.

One way to do this is to place the fish tank in your freezer if it can fit. Putting the fish tank outside can lower the temperatures drastically if you live in a cold area. Like the other methods, remove living organisms like plants and fish from the tank before reducing the temperatures.

After the job is done, you can return the fish tank to its usual location. Wait until the temperatures have stabilized before returning the fish to this main tank. This method isn’t without its downsides, though.

Lower temperatures can also kill beneficial bacteria that are necessary for freshwater aquariums.

Many fish keepers believe there is no way you can kill scuds that won’t kill fish or harm plants and other living creatures in the tank. But some swear that increasing carbon dioxide levels in the freshwater aquarium will do the job without destroying a planted tank.

Although you have to deconstruct your tank, this is a method that can kill a large scud population.

Tips to Prevent Aquarium Scuds From Populating

Here are some additional tips to prevent scuds in your fish tank:

  • Before placing fish into the main tank, quarantine everything, including new fish, plants, and decor like driftwood.
  • Stop overfeeding your fish. While this might help for a while, scuds always find something to eat in the fish tank. Some scuds can also survive days without food, so trying to starve them out may not be completely effective.
  • Constantly check and clean the tank’s filter. Aquarium scuds are known to hide and eat the waste trapped in sponge filters.

Do You Want Scuds in Your Home Aquarium? 

Although most aquarists have different opinions on whether or not scuds should be left to thrive in a home aquarium, they can cause problems in any fish tank. If you want your fish to be happy and healthy, it’s best to remove scuds from your tank before they form a colony and overrun it.

Manually removing scuds from the fish tank is one of the best ways to control their population, but very time-consuming. You can use scud traps because once the scud is caught, it can’t escape.

Scuds are an advantage if you’re looking for an additional food source for your fish, but they can also be a menace if you have fish fry or breeding shrimp in your freshwater aquarium.


Can you use chemicals to remove scuds? 

No. And you shouldn’t try and use chemicals because they can harm your fish and plants in the tank. While it can kill scuds, it will also kill plants and other aquatic life in freshwater aquariums. They are very hardy, so you’ll need strong chemicals that will damage all living creatures in your tank.

How do I get rid of scuds in a shrimp tank?

The best way to kill scuds in a shrimp tank is by first removing the shrimp and increasing the CO2 levels in the tank. This will suffocate the scuds, and you can return the shrimps to the main shrimp tank after you have recycled the water and ensured the water is safe for shrimp keeping.

Does AlgaeFix Overdose treatment work to get rid of scuds?

While some fish keepers have found this treatment helpful, the product’s description states that you shouldn’t use it in a tank with crabs, freshwater shrimp, freshwater lobsters, or other freshwater crustaceans. Remove them from the tank first before using this mixture to kill scuds.

Are scuds fish?

No. Scuds are a crustation that is more similar to shrimps than fish. Scuds have legs and a shell, unlike fish.

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