How to Clean a Fiddler Crab Tank

Fiddler crabs are small, easy pets to take care of and are easier than fish. They create a lot of waste, though, so many people who don’t know how to clean up after them and don’t bother. However, you can clean their tank simply enough! Follow these steps to make sure your crabby friend has a clean place to live.


EditDoing a Partial Clean

  1. Suck up any detritus. Using a gravel siphon or turkey baster, remove bits of food and poop. Fiddler crab poop looks like tiny brown dots about the size of their eyes, and because of their small size they are easy to take out. Try not to suck up too much sand, or you’ll just be dumping it away.
    Clean a Fiddler Crab Tank Step 1.jpg
    • Move the sand around a little to uncover some waste that may have been buried.
  2. Do a partial water change. Change 15-25% of water volume, and remember to add a water conditioner and 1/2 teaspoon of marine salt per 1.5-2 liters of water[1].
    Clean a Fiddler Crab Tank Step 2.jpg
    • If there’s floating waste in the water, quickly scoop it out with a fish net before it settles.
  3. Clean decorations and food bowls (if any). Use a 5-10% bleach solution[2] to soak non-absorbent decorations for no more than 10 minutes. Rinse and dry them thoroughly. If you want to scrub them, then you can when rinsing. For live plants or absorbent materials like wood, soak in slightly salty water (made with a few teaspoons of salt in 1.5-2 liters of water) for 10 minutes and scrub with a clean tool.
    Clean a Fiddler Crab Tank Step 3.jpg
    • Always let the objects dry fully before placing them back in the tank. If you used bleach, make sure there is no bleach smell left.

EditDoing a Full Clean

  1. Unplug everything and move the crabs to a holding container. A bucket with a shallow level of warm, dechlorinated brackish water works. When removing the heater, always pull the electrical plug first and then wait 15 minutes before removing it from the water.
    Clean a Fiddler Crab Tank Step 4.jpg
    • If the electrical plug to an appliance is wet, do not pull it out, until you dry it.
  2. Clean the appliances. Take out the filter cartridge and set it aside in a container of tank water. This will keep some beneficial bacteria. Rinse the heater, filter, and air tube/stone (if using) in running water. Rub with a cleaning pad or your hands to clean out filth. Pat dry or let air dry.
    Clean a Fiddler Crab Tank Step 5.jpg
    • Make sure that water doesn’t drip from the appliances to their plugs. If you do get water on the electrical plugs, let them air dry to dry out fully. Do not plug in and use when wet.
    • Only wash the main body of the appliance.
  3. Clean the decorations and sand. Cleaning the decorations is the same as described in step three of “Doing a Partial Clean”. The sand, however, can’t just be soaked and rinsed. Suck up waste using the siphon/turkey baster to get rid of the easy waste first. Drain off as much water as you can. Place the sand in a bucket and fill the bucket with tap water. Swish the sand around inside the bucket to clean it, then drain off the water. Repeat until the water does not have any floating bits of waste.
    Clean a Fiddler Crab Tank Step 6.jpg
    • You can replace some of the old sand if you want, and it is recommended that every few months that you do so.
  4. Wash the entire tank. First rinse out any sand. If you feel that the tank needs a thorough disinfection, let a 10% bleach solution sit inside for 10 minutes. If there is a hard water stain/salt stain but you don’t want to use bleach, spray the walls of the tank with vinegar and let it sit for five to ten minutes. Scrub every corner of the tank if necessary, and rinse out. Let the tank dry outside until the bleach/vinegar smell is gone and it is completely free of water. If you can’t do outside, you can place it in a well-ventilated room.
    Clean a Fiddler Crab Tank Step 7.jpg
  5. Replace all of the decorations and appliances. Add the sand first. If you have a big decoration, you can add that in next, so when you place the water in, you can pour it on the decoration (as not to disturb the sand). If you have delicate decorations, add them after adding water. Add the water, and then the filter, heater, etc. For the heater, place the body in the water for 15 minutes before plugging it in. Wait for the heater to warm the water if you used colder water, then add in anything else (decorations, plants). Finally, add the crabs in.
    Clean a Fiddler Crab Tank Step 8.jpg
    • Make sure your water is treated and brackish.


  • A partial clean can be done once every one to two weeks, and a full clean every few months.
  • Reserve cleaning materials for crab-use only to prevent contamination.
  • Always clean decorations and food bowls outside of the tank so you don’t bother the crabs.
  • You don’t have to change the filter cartridge unless it is not working, is falling apart, or very dirty. Sand may make your filter cartridge dirtier faster. Rinsing will clean out most of the gunk (wash in treated water!).
  • For ease of cleaning, you can put fine gravel in the water area of the tank. Although many people debate about gravel vs. sand, with many saying sand is best[3] and that gravel hurts the crabs. If you absolutely can’t do all sand for some reason, fine gravel in the water is okay.
  • Always make a drip loop in the appliances’ cords. Brackish water conducts electricity better than fresh, so you want to make sure you don’t electrocute/shock yourself or the crabs.


  • Don’t use more than 10% bleach or soak for more than 10 minutes. It can discolor and damage your decorations.
  • Scented or colored bleach will not work here.
  • Removing the heater from the water without waiting for it to cool after unplugging it (or not unplugging it) can lead to the heater glass cracking (temperature difference).
  • Cleaning the sand while in the tank is not recommended because it can scratch the glass walls.
  • Bleach should only be used if your tank/decorations are really in need of it.
  • Make sure the other organisms, if any, living with your crabs can take the salinity.

EditThings You’ll Need

  • Gravel siphon or turkey baster
  • Bucket
  • Scrubbing pad or tool
  • Marine salt
  • Water conditioner
  • Bleach
  • White vinegar

EditRelated wikiHows

EditSources and Citations

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