What Does it Mean When Fish Rub the Floor?

If your fish are rubbing themselves against the floor of their aquarium, it's not a cute or eccentric behavior -- unfortunately, it's a sign of parasites. These parasites cause discomfort to their skin, and they rub against surfaces to try and remove them. You'll need to intervene and treat the fish if you see this behavior.

  1. Other Symptoms

    • If you see a fish rubbing itself against the floor or decor of an aquarium, take a closer look. More often than not, you'll notice signs of parasites at this point. The two most common are ich and velvet. These are both protozoan parasites. In ich, the parasites form cysts on the skin that look like grains of salt. In velvet, the cysts look more like yellowish powdered sugar. Even if you can't see cysts yet, you need to treat the fish for parasites if you see them rubbing their bodies against surfaces.

    Salt and Heat

    • Salt and heat are the traditional treatments for parasites. To treat fish with salt, mix salt and aquarium water in a bucket; don't add the salt directly to the aquarium. First, dissolve about 2 to 3 teaspoons of salt per gallon of aquarium volume in the bucket. Once the salt is totally dissolved, slowly pour the bucket water into the aquarium. Do this slowly, adding a little at a time over the course of an hour. Then, raise the aquarium temperature to between 82 and 86 degrees Fahrenheit. Often, this will clear up parasites like ich and velvet in about a week. Keep in mind that some fish, like cory catfish and some tetras, don't tolerate salt and high temperatures well.

    Medications

    • If you need to resort to aquarium antibiotics, you can pick these up at most pet shops. Follow the manufacturers' instructions to the letter, as many aquarium medications can be toxic if used incorrectly. Also, remove all carbon and zeolite from the aquarium, since these materials tend to absorb medication from the water.

      Keep in mind that antibiotics can harm the bacteria in the gravel that break down fish waste. So you'll want to monitor closely the ammonia and nitrite levels when treating the tank.

    Quarantine

    • The best way to avoid parasites like ich and velvet is to quarantine fish before adding them to the main tank. To quarantine fish, keep them in a small tank with similar water conditions to the main aquarium. Feed them regularly, and look for signs of ich and velvet, like rubbing themselves against surfaces or visible cysts. If you see these signs, it's easier to treat the disease in the quarantine tank than the main tank where it can spread. However, if you get ich or velvet in the main aquarium, you need to treat the entire tank, rather than moving just one fish to quarantine, since most parasites have a free-swimming stage.