Why Is My Guppy Laying On The Bottom Of The Tank? (8 Possible Reasons)

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It is not normal for guppies to lay on the bottom of the tank. In my experience, there are a number of reasons guppies lay on the bottom of the tank and these include illness, stress, and poor water quality. Pregnant females may also lay on the bottom of the tank prior to giving birth.

Anyone who has kept guppies before will know why they are one of the world’s most popular freshwater fish. Guppies are friendly, colorful, hardy, and easy to breed. They fit well into just about any community tank and for most people, guppies are the first fish they successfully breed.

I first started keeping guppies over 30 years ago when I was given a 10-gallon aquarium with a small group of guppies. From that point onward I was hooked and I don’t think a day has gone by when I didn’t have a tank of guppies in my fish room.

Why Is My Guppy Laying On The Bottom Of The Tank?

Guppies are active swimmers that spend a lot of their time swimming around the aquarium looking for food or trying to mate with females. If your guppy is laying on the floor of the aquarium, it is usually a sign something is wrong.

The main reasons guppies lay on the bottom of the aquarium include;

  • Pests or Disease
  • Stress caused by:
    • Poor Water Quality
    • Incorrect Water Parameters
    • Bullying by other tank mates
  • Swim Bladder Issues
  • Pregnant Female in Labor
  • Guppy is a new inhabitant of the tank

Pests and Diseases

One of the best qualities guppies boast is their hardiness. However, even a fish as hardy as a guppy can occasionally become sick. If you have a guppy that is just sitting on the bottom of the aquarium, take some time to observe the fish and see if it has any obvious signs of illness.

In my experience, the most common pests and diseases that affect guppies include Ich, fungus, bacterial infections, internal worms, and constipation (constipation isn’t technically a pest or disease, but we’ll include it here anyway).

The table below details some of the most common pests and diseases and lists their symptoms and treatments.

Ich (also known as whitespot)Ich usually presents itself as small white spots, often on the fins, which overtime increase in number until they overwhelm the guppy
I have had great success treating Ich with Ich-X from Hikari (more information in this article Why do my guppies have white spots?

Fungus and Bacterial InfectionsA fungus growing on a guppy usually presents itself as a white, cotton-like growth, often around the mouth or near an open wound.The most reliable treatment I have found for guppy fungus is Maracin which is made by Fritz. Maracin treats all manner of bacterial infections and funguses and is safe to use in planted tanks. (eSHa 2000 if you are based in Europe)
Internal Parasites (tapeworms)Guppy may be swollen, have no appetite, or maybe passing white, stringy poop (see article here about why does my guppy have white stringy poop?)ParaCleanse, which is made by Fritz, is an excellent treatment for internal parasites. I use ParaCleanse both to treat my guppies, and as a preventative measure in my quarantine tanks.
ConstipationConstipation usually leads to a guppy having a very swollen stomach, sometimes to the point the guppy can no longer swim.The simplest way to ease constipation is to move your guppy to a separate tank and give an Epsom Salt bath. Feeding Brine Shrimp or crushed peas can also help constipation pass.


Guppies are easily stressed. Stress is a guppy killer and there are many different reasons guppies can become stressed. Poor water quality can be very stressful for guppies as can incorrect water parameters like temperature and pH. Bullying by other fish can also be very stressful for guppies. We can look at each of these potentially stressful issues below.

Poor Water Quality

People are often surprised by how quickly water quality can deteriorate, even if we are using a good quality filter on our aquariums.

Overfeeding our fish is a classic way we lower our water quality. I like to feed my fish little and often, rather than all in one go. Adding a little food at a time allows us to observe how much food our guppies are eating before adding more. If we just drop a giant pinch of food into our guppy tank, then walk away, a lot of the food will drop down behind rocks or into the plants where it is uneaten and starts to rot.

It can sometimes be tricky to know how much to feed our guppies, especially if we are new to keeping guppies. I recently wrote an article titled How Often Should You Feed Guppies? which offers some good advice about how much and how often to feed guppies.

Incorrect Water Parameters

If the water our guppies live in has incorrect water parameters the guppies can quickly become stressed. The correct water parameters for guppies would be the following;

  • Temperature: 72-82 °F (22-28 °C )
  • pH: 6.8 – 8.0
  • Hardness: 8-12 dGH
  • Ammonia: 0ppm
  • Nitrite: 0ppm
  • Nitrate: less than 40ppm

I use a good-quality test kit to monitor my guppy water parameters. The API Master Test Kit for freshwater aquariums has always proved reliable for me (I bought this one from Amazon.com).

Guppies are tolerant if your parameters are slightly different from those listed above, but if your water is vastly different, your guppies may begin to suffer.

Bullying by other tank mates

Bullying by other tank mates doesn’t just mean by other, bigger fish. Male guppies are very persistent breeders, and if your males outnumber your female guppies, the constant desire to breed can become very stressful on the female guppy.

I like to try to keep at least 3 female guppies for every 1 male. That way the attention is spread out and the females aren’t being continually hassled.

If you do have larger, more aggressive fish in with your guppies, consider rehousing the bully fish. Guppies are not fighters and they can easily be bullied to death.

Swim bladder Issues

Guppies, like almost all fish, have an internal organ called a swim bladder. The swim bladder’s job is to keep the fish neutrally buoyant so the guppy can remain static in the water without having to constantly swim.

Often swim bladder issues present themselves as the guppy not being able to stay upright. Guppies with swim bladder issues are frequently seen swimming upside down or floating near the surface. This article titled Why is my Guppy Swimming Upside Down has some really good information about guppies with swim bladder issues.

Sometimes, a guppy with swim bladder issues has the opposite problem. Instead of the swim bladder being swollen, causing the guppy to float, the swim bladder is perforated and the guppy struggles to get off the ground.

I had a bright blue male guppy once that spent months bobbing along the bottom, never really leaving the substrate. I am certain he had a perforated swim bladder.

Pregnant Female Guppy in Labor

It is not uncommon for a heavily pregnant female guppy to need to rest during her labor. If you have a large, female guppy sitting on the aquarium floor, it probably isn’t anything to worry about.

Give her a few hours and she will probably swim back up and pass the rest of her babies.

Guppy is new to the tank

If you have a guppy that is just sitting on the bottom of the tank, and you have only just added it, it is probably just adjusting to its new surroundings. Guppies can go into a shock-like state when they are first added to a tank and it can take them a couple of hours to adjust to their new surroundings.

If you have just added some guppies and one is sitting on the bottom. Give it a few hours before you become too concerned. It will probably swim around once it adjusts.

When I move new guppies from my quarantine tanks to their new aquarium, I often find one or two of them will ‘sink’ straight to the floor and just sit there. They normally start to swim around and join their tank mates after an hour or two.

What To Do With A Guppy Sitting On The Bottom Of The Tank?

If one of your guppies is sitting on the bottom, and not swimming around, take some time to observe the guppy and see if one or more of the potential issues listed above fits your guppy.

If your guppy is unwell, treat it with appropriate medication. If you think it may be stressed, use a test kit to check the water parameters. Working out why a guppy is just sitting on the bottom increases the chance you can fix the problem.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

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