Last update: April 24, 2023

15 Best Fiddler Crab Tank Mates – FishLab

The fun and feisty fiddler crab is a popular pet, and it isn’t difficult to see why. With unique colors and patterns, they make for an attractive addition to your habitat, and male fiddler crabs have the feature that lends this incredible animal its name – an enormous front claw that can sometimes be as large as their whole body! 

If you fancy the idea of adding other species to your habitat alongside your fiddler crab, you have to be careful when choosing tank mates. While fiddler crabs are social and enjoy some company, certain animals may not be compatible with this energetic species. The best Fiddler Crab Tank Mates are as follows: 

  • Black Skirt Tetra
  • Creamsicle Lyretail Molly
  • Bumblebee Goby
  • Endler’s Livebearer
  • Leopard Guppy
  • Dalmatian Molly
  • Double Swordtail Guppy
  • Golden Sailfin Molly
  • Montezuma Swordtail
  • Tuxedo Guppy
  • Sheepshead Swordtail
  • Harlequin Sailfin Molly
  • Black Marbled Swordtail
  • Zebrafish
  • Snakeskin Guppy

Read on to learn more about the best fiddler crab tank mates, as well as basic care and feeding of fiddler crabs. 

Fiddler Crab Tank Mates – What you Need to Know 

As great as fiddler crabs are as pets, there are some key things you must know before adding another species to their tank. 


Fiddler crabs are energetic, social, and active creatures. They’re not necessarily aggressive, but male crabs can get territorial and competitive over a female. If you see two male fiddler crabs fighting, it’s best to place them in separate tanks to keep them from injuring each other. 

The best tank mates for fiddler crabs are peaceful and fast-moving, able to coexist well with the crabs and keep out of reach of their claws. The best species are livebearers that can use the best 


Fiddler crabs, unlike aquarium fish, need little space to thrive. You’ll need about 2.5 gallons of total tank space for each fiddler crab, meaning a 10-gallon tank could hold up to four fiddler crabs comfortable.

However, when it comes to adding a tank mate of a different species, the space needs of the other species needs to be taken into account. For smaller fish, like mollies and guppies, the rule of thumb for space is the one inch per gallon rule, meaning that you could have 5 one-inch fish in a 5-gallon tank. 


Fiddler crabs are omnivores and scavenge by instinct. They’ll eat algae, tiny insects, and fungus from the substrate by sucking it into their mouths and spitting it out. With this in mind, they’ll also see smaller species that remain near the substrate – such as small shrimp or snails – as food and will try to eat them. 

Avoid aggressive fish species such as cichlids or sharks, as they may stress and injure the crabs. Peaceful fish species that are quick enough to avoid being snapped by the crabs’ claws are ideal. 

Aside from algae and dry food such as pellets and flakes specifically designed for crabs, fiddler crabs also eat bloodworms, brine shrimp, plankton, blanched zucchini, and seaweed, so the ideal tank mate won’t compete with them for food. 

Parameters ; Tank Setup 

Fiddler crabs aren’t freshwater species, preferring brackish water with low saline levels. Their ideal water parameters are listed below: 

  • Water temp: 75 – 85 degrees Fahrenheit
  • pH levels: 8.0 – 8.3
  • Water hardness: 12 – 30 KH

Tank mates, such as guppies, tetras, mollies, and swordtails, will thrive well in brackish water but may need time to fully acclimate to the brackish waters. Using aquarium salt to gradually adjust the water to ideal salinity is best. 

Fiddler crabs will need a tank with mostly water, but will also need an artificial shoreline with fine, sandy substrate in which to burrow and dig. This gives the fiddler crabs room of their own that they won’t have to compete over with fish species. 

Don’t use gravel or crushed shells, as it is sharp, hard, and is impossible for the crabs to burrow into. Gravel and shells may also injure your fiddler crabs. 

Within the tank, it’s important to add decorations such as rocks, driftwood, and plants (real or artificial, though keep in mind that the fiddler crabs might try and eat real plants) for the crabs to climb over. The tank mates will also thrive in environments with plenty of hiding places, and real plants will add oxygen to the water. 

15 Best Fiddler Crab Tank Mates

Because of the brackish water in which fiddler crabs live, there aren’t many fish who can withstand the water parameters. Many fish may also be mistaken for food with the fiddler crab, especially slow-moving fish that can easily be snatched up by the quick fiddler crabs. If the tank mates are too small, they may also be mistaken for food – especially if they are also slow.

However, the following tank mates have been successful sharing a habitat with these fun crustaceans. 

You also shouldn’t miss:

1. Black Skirt Tetra

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  • Scientific Name:  Gymnocorymbus ternetzi 
  • Adult Size:  3 inches
  • Compatible with:  crabs, snails, gobies, mollies, guppies, gouramis, and any peaceful fish of a similar size. Avoid pairing with fish with long, flowing fins (such as angelfish or swordtails) and aggressive species such as bettas. 
  • Care Level:  Beginner
  • Origin:  Paraguay, Argentina, Brazil

The Black Skirt Tetra has a flashy appearance that works well with your colorful fiddler crab. The black skirt tetra is omnivorous, meaning that it and the fiddler crab will eat the same kinds of food, simplifying the feeding needs of your tank. 

Black skirt tetras generally need a minimum tank size of 15 gallons, meaning your simple 10-gallon fiddler crab tank won’t be sufficient. They may also compete for the same food, given their omnivorous nature. Black skirt tetras also prefer slightly acidic water, meaning they may not do well in a crab’s more basic environment. 

2. Creamsicle Lyretail Molly

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  • Scientific Name:  Poecilia latipinna
  • Adult Size:  4 inches
  • Compatible with:  Peaceful livebearers such as guppies, other mollies, tetras, snails, crabs, gobies, and swordtails. 
  • Care Level:  Beginner
  • Origin:  Southern Mexico

Prefers the same pH and salinity as fiddler crabs, so water parameters aren’t as much of a concern. Lovely cream and orange colors make for a beautiful display alongside the colorful crabs. 

Flowy fins might be easy for crabs to pinch. Creamsicle lyretail mollies also may compete for food, especially the flakes, which they have the ability to suck inside their large, extruding mouths. They can grow up to 4 inches in length, meaning they’ll need a larger tank with lots of room. 

3. Bumblebee Goby

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  • Scientific Name:  Brachygobius xanthozonus 
  • Adult Size:  1.5 inches
  • Compatible with:  Peaceful livebearing fish such as guppies, mollies, gobies, swordtails, tetras, crabs, shrimp, and snails. 
  • Care Level:  Moderate 
  • Origin:  Thailand and Indonesia

This small fish only grows to 1.5 inches in length, so they’ll thrive in a compact fiddler crab tank. They won’t compete for food with the fiddler crabs for pellets or flakes because they prefer frozen or live food. 

It is recommended that bumblebee gobies are purchased in minimum group sizes of 6, as they can become aggressive towards other species if they don’t have the protection of a school. They require a lot of live plants and driftwood in the tank. 

4. Endler’s Livebearer

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  • Scientific Name:  Poecilia wingei 
  • Adult Size:  1 – 2 inches
  • Compatible with:  Small, peaceful fish, snails, and crabs
  • Care Level:  Moderate
  • Origin:  Venezuela

These colorful and peaceful fish get along well with fiddler crabs. They’re small and don’t need much space.Fry may be mistaken for food, which may or may not be a bad thing if the Endler’s livebearer population in your fiddler crab tank is out of control. They breed easily with each other and with guppies, so keep this in mind if you have guppies as tank mates. 

5. Leopard Guppy 

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  • Scientific Name:  Poecilia reticulata 
  • Adult Size:  1 inch
  • Compatible with:  Most peaceful species that won’t mistake them for food
  • Care Level:  Beginner
  • Origin:  South America

Beautiful patterns and long, flowing tails are a great aesthetic addition to a fiddler crab tank. They’re small and easy to care for. Leopard guppies, like other guppies, are hardy and can tolerate a wide range of temperatures and water parameters. Because of their small size, they may be mistaken for food by the fiddler crabs. 

6. Dalmatian Molly

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  • Scientific Name:  Poecilia latipinna 
  • Adult Size:  4 – 5 inches
  • Compatible with:  Peaceful fish species, snails, and crabs
  • Care Level:  Beginner
  • Origin:  Southern Mexico

Like other mollies, the Dalmatian molly can tolerate a wide range of salinity levels in their tank. They’re easy to care for. Because they require algae in their tank, they’re compatible with the algae-loving fiddler crabs. Can grow up to four inches long, which means they’ll need a bigger tank. Might compete for food with the fiddler crab. 

7. Double Swordtail Guppy

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  • Scientific Name: Xiphophorus helleri  
  • Adult Size: 5 – 6 inches
  • Compatible with:  Peaceful aquatic species of a similar size
  • Care Level:  Beginner
  • Origin: Central America, Mexico, Belize, Guatemala

The eye-catching tails of the double swordtail guppies are a great addition to any tank. Guppies are hardy and can tolerate a range of water parameters.Double swordtail guppies can grow very large, up to 6 inches long, and will need a large tank in which to keep them. 

8. Golden Sailfin Molly

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  • Scientific Name: Poecilia latipinna
  • Adult Size:  5 inches
  • Compatible with: Peaceful aquatic species of similar size, snails, and crabs
  • Care Level:  Beginner
  • Origin:  Southern Mexico

Golden sailfin molly are beautiful and easy to care for. Sensitive to water parameters and may need to be acclimated to the brackish water inside a fiddler crab tank gradually. They can also grow quite large, requiring more space. 

9. Montezuma Swordtail

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  • Scientific Name: Xiphophorus montezumae 
  • Adult Size: 3 inches
  • Compatible with: Peaceful species that won’t mistake it for food
  • Care Level: Moderate
  • Origin: Northeast Mexico

These fish are eye-catching and colorful, and can tolerate a broad range of water parameters. Montezuma swordtails need a lot of space, such as a 15-gallon tank for a single swordtail. 

10. Tuxedo Guppy

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  • Scientific Name: Poecilia reticulata 
  • Adult Size:  2 – 3 inches
  • Compatible with: Peaceful fish, snails, shrimp, and crab species
  • Care Level: Beginner
  • Origin: Northern South America

Tuxedo guppies are hardy, adaptable, and don’t need much space. The tuxedo guppy is also very rare, adding value to a hobbyist aquarium. Still, you need to be purchased in small groups to thrive. 

11. Sheepshead Swordtail

  1. Scientific Name: Xiphophorus birchmanni 
  2. Adult Size:  2 – 3 inches
  3. Compatible with: Peaceful fish, snails, shrimp, and crabs
  4. Care Level:  Beginner – Moderate
  5. Origin:  Mexico and Central America

Can tolerate a wide range of temperatures and water parameters. Omnivorous and not picky about food. Males are highly competitive, and need to be in groups where females outnumber males. Require densely planted live plants in their tank. 

12. Harlequin Sailfin Molly

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  • Scientific Name: Poecilia latipinna
  • Adult Size:  5 inches
  • Compatible with: Other peaceful aquatic species as well as snails, shrimp, and crabs
  • Care Level: Beginner
  • Origin: Southern Mexico

Harlequin sailfin mollies are very colorful, hardy, and tolerant of a broad range of water parameters.Need a lot of space, with a 20-gallon tank the minimum size for a single harlequin sailfin molly. 

13. Black Marbled Swordtail

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  • Scientific Name: Xiphophorus hellerii 
  • Adult Size: 
  • Compatible with: guppies, platies, danios, mollies, gobies, gouramis, snails, shrimp, and crabs – any peaceful species of the same size
  • Care Level: Beginner
  • Origin: Mexico and Central America

Easy to care for, tolerant of a wide range of water parameters, and eats the same food as fiddler crabs. May compete with fiddler crabs for food and needs a minimum tank size of 20 gallons. 

14. Zebrafish

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  • Scientific Name: Danio rerio
  • Adult Size: 1 – 2 inches
  • Compatible with: any peaceful aquatic species such as crabs, snails, shrimp, mollies, guppies, other danios, gouramis, swordtails, and gobies. 
  • Care Level: Beginner
  • Origin: South Asian nations such as India, Bhutan, Pakistan, Bangladesh, and Nepal. 

Easy to care for and tolerant of a wide range of water parameters. The smaller fry may be mistaken by the crabs for food. 

15. Snakeskin Guppy

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  • Scientific Name: Poecilia reticulata 
  • Adult Size:  2.5 inches
  • Compatible with: Peaceful aquarium fish as well as snails, shrimp, and crabs. 
  • Care Level: Beginner
  • Origin: Northern South America

Flashy, eye-catching appearance. Vibrant colors and patterns, hardy and adaptable. This rare variety of guppy also increases the value of a hobbyist’s aquarium. Long flowing tail poses a risk of being snapped by the fiddler crab’s claws. 


While fiddler tanks do best in a single-species tank with others of their kind, there are several tank mates that suit a fiddler crab tank. The best tank mates for fiddler crabs are peaceful, live-bearing fish that can tolerate brackish waters and are large enough not to be mistaken for food. The best fiddler crab tank mates are mollies, tetras, guppies, gobies, and swordtails. 


Can fiddler crabs live with fish? 

The best tank mates for fiddler crabs include peaceful, live-bearing fish such as mollies, guppies, gobies, swordtails, and tetras. 

How many fiddler tanks can I have in a tank? 

Up to four fiddler crabs can comfortably fit in a 10-gallon tank. 

Are fiddler crabs a freshwater species? 

Fiddler crabs prefer brackish water, which has low salinity. 

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

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