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This is an amphipod in my aquarium. Also known as Scud's.

Shrimp Like Creatures in My Fish Tank (How to Get Rid of Scuds)

A couple of months ago, I was looking at my 10-gallon freshwater aquarium and noticed something moving in the gravel. I looked closer and found what looked like teeny tiny shrimp. That’s what it looked like at first, once I took a closer look, I could see it wasn’t a shrimp at all. Then I noticed another and another and another! My substrate was infested with these little shrimp-like creatures. I must admit, it really grossed me out, at first.

What are tiny shrimp-like creatures in a freshwater aquarium? Commonly found in freshwater aquariums where there is an overabundance of organic materials such as excess fish food and fish poop, you will find amphipods called scuds. Scuds are not harmful to freshwater aquariums. Scuds eat decaying plants, excess fish food, dead fish, fish poop and anything else organic and decaying. 

In their natural habitat, which is typically not in an aquarium “on purpose”, scuds can be found in shallow freshwater streams, ponds, rivers and lakes. I say on purpose because who would want these creepy little critters in their tanks? With that being said, I am sure there are some resourceful hobbyists that would find some use for them. Maybe a food source for some fish or a way to help keep their substrate clean.

I, on the other hand, do not want these creatures in my tank. That is why I wrote this article, as I have done some research and I am now ready to battle my scuds until they are no more. If you have found these grotesque creatures in your freshwater tank and want them gone, keep reading and I will share to successfully (fingers crossed) get your aquarium of scuds. Let’s get to it!

 

How to Identify Scuds in Your Fish Tank

The best way I could describe them is, at first glance (to me), they looked like tiny shrimp. As a matter of fact, that’s what I thought they were at first, until I researched them.

If you take a closer look you will see that scuds have two sets of antennae. When moving about, they wiggle and flex their “arched” bodies as they move about on their sides. It is the shape of their bodies that makes them look like a shrimp. I just find them to be really, creepy ugly little creatures. Source.

They are about ¼” to ¾” in length. I haven’t seen any that big in my aquarium yet or I would be scooping all the gravel out and into the garbage. The ones in my tank are mostly about 3/16” however, I have found a couple just slightly larger.

I am attaching some of my own pictures to this article and hopefully they give you a really good idea of how these little critters look.

freshwater scud in my fish tank

This is a scud in my 10 gallon aquarium.

How Do Scuds Get in Your Aquarium in the First Place?

If you do find scuds in your fish tank, you better get rid of them quickly as they multiply faster than rabbits. I do a partial water change every weekend by vacuuming the gravel, which picks up any scuds in the vicinity.  The amount of scuds I find sucked up into the pail amazes me every time! At this point, I am just maintaining the population and will have to take drastic measures to rid my aquarium of them.

Before we talk about how to get rid of them, let’s identify how they get in your aquarium in the first place. They don’t just appear out of thin air so how did they get in there?

Scuds will travel on live plants from your local fish store or if you have used substrate they could have been in there already. If you ever get used aquarium components like filters or decorations, they could have been in those items as well. They are so small that it would be easy to miss them and add them to your tank. In my case, I believe it was some live plants I purchased from my local fish store.

 

How to Get Rid of Scuds

Scuds are so invasive and very difficult to eradicate. As I mentioned earlier, I have been siphoning my tanks gravel every week and all I am doing is keeping the numbers at a reasonable level. Let’s talk about some ways you can try to get rid of these pesky creatures.

  • If you are not in a hurry, you can try adding a couple slices of zucchini into the tank overnight. This will attract the scuds and without turning on the lights, you should find the zucchini covered with them. Before the lights turn on slowly, reach into the tank with a net and scoop out the zucchini. Rinse off with very hot or freezing cold water. Repeat this every night consecutively until you notice no more scuds on the vegetable.

 

  • A more drastic option is to freeze the gravel and water. This doesn’t mean literally turning the water into ice as that would be ridiculous! This technique can be done with small tanks only.
    • What you do want to do is take out all living creatures you want to save along with plants. Take out as much water as you can and dump it.
    • Place the tank in a fridge or freezer or outdoors, if you live in a cold region. After an hour or so, the temperature around the substrate and the water should dip low enough that it will kill anything living.
    • Once done, put your tank back into place and top up the water. I would recommend changing out all filters, as there could be scuds in them. Once your tank is back up to the correct temperature, you can place the fish back in.
    • Going this route is a lot of work but should kill all off the scuds, leaving beneficial bacteria in place.

 

  • You could try scooping out the substrate and boiling it. You would need to do a bleach dip with the plants or throw them out and change out the filtration material as well. The two problems with this method include:
    • You are boiling and killing the beneficial bacteria. Your tank will have to go through another nitrogen cycle. This means your fish will have to be moved or they will die.
    • There will most likely be some scuds you don’t notice swimming in the water and will get missed when you take out the substrate.
    • Therefore, this method sounds like it might work however, you are basically starting your tank from scratch again.

 

  • You can try purchasing fish that eat scuds. Any smaller tropical fish should eat them. That’s the recommendation I have read however, I have a school of neon tetras and they don’t seem that interested in the scuds. Also, I have dwarf corydoras  (catfish) in that tank and I don’t think they could care less either. Loaches have been reported to help with scud issues.

 

Conclusion

It is important to note that when you first notice these little creatures in your aquarium, you must take action immediately or they will multiply until there are so many that you will need to take drastic measures to rid the tank of them.

On the other side of this, a scud is not technically a problem for freshwater aquariums. It just depends on how pristine you want your aquarium to look. In my case, the scuds destroyed my live plants, so they needed to go. I would rather have live plants living and growing in the aquarium than those creepy looking freshwater amphipods.

Whatever you decide to do, I wish you the greatest success. Scuds, yuck!

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freshwater scuds in your aquarium