One of several species that are hard to identify, the Bridled Goby has a tell tail notched pelvic fin along with a dark colon shape at the base of the tail! 

The Bridled Goby varies in color, depending on their location.  Adults found on white sandy bottoms and clear waters are pale with horizontal rows of pale yellow, orange and iridescent blue and white spots.  Some can have small light thin brown “x” shapes down the sides of their bodies.  They have a partial horizontal orange “eye bar” streak that runs from the middle of the eye, horizontally and stops near the pectoral fin.  This eye bar can be underscored in black, and in some light it can have a black to brown appearance.   They also have small, spaced, dark spots that run the length of the fish, located on the top of their back and their dorsal fins are clear.  They also have a dark colon “:” shape at the base of their tail fin, although the juvenile’s colon is not as prominent.   Darker versions of this fish come from areas with  darker substrates and water that is more turbulent.  They have a darker over all color and rows of brown “x” that run down the sides of the body.  The darker specimens have dusky fins as well.  This one also has the partial horizontal orange streak that runs from the middle of the eye and ends at the front of the pectoral fin.  They have oversized, notched in the middle, pectoral fins  which they use to perch on and like all gobies, lack a swim bladder.  They only reach 3” (8 cm) and they probably only live around 4 years like most gobies.  The Bridled Goby is a beginner fish.

There is a lot of confusion when it comes to the identity of this fish.  In the beginning, several of these species were lumped into one, due to quick visual inspection.  Snaps to BlueZooAquatics for having the correct picture for this species, however the term Cave Goby is catching on and confusing aquarists.  This fish actually has one accepted common name, Bridled Goby (C. glaucofraenum), so while common names are important, knowing the scientific names is of primary importance for the Coryphopterus genus.  Many online websites have a picture of a the Interspotted Sandgoby, Fusigobius inframaculatus (previously Coryphopterus inframaculatus, with the extended dorsal fin), and are calling it the Transparent Cave Goby or the Bridled Goby.  A quick look at will reveal the correct identities.  Adding to that, other websites have photos of the Pale Sandgoby, (Fusigobius pallidus), and are calling it the Transparent Cave Goby.  Again, a quick trip to Fishbase shows they are incorrect also, since the Pale Sandgoby has a black spot on the front of it’s first dorsal fin.  The Bridled Goby is similar several different other sand gobies, including C. bol, C. Eidolon, C. Venezuelae, C dicrus, and C. tortugae.  The differences are discussed below.  Simply put for this fish, the Bridled Goby has a colon or “:” shape at the base of the tail fin.  One researcher suggested the common name Colon-tail Goby, instead of Bridled Goby, because of this feature since it is more pronounced than in C. dicrus.   

The Bridled or Colon-tail Goby is easy to care for and great for beginners and those who have nano tanks!  Like most bottom dwelling gobies, this fish is easy to feed and will readily accept frozen thawed mysis, brine, and finely minced meaty marine crustacean flesh.  There are other gobies from this genus that feed on some benthic weeds and algae so it is possible they may need veggies as well.  Resisting the urge to buy larger fish like large wrasses from Thalassoma genus, groupers, lion fish and eels is wise, due to their taste for small fish!  Sand would also be the necessary substrate and any lighting is fine.

Tank mates would be any peaceful fish that would not scare your Bridled Goby into hiding all the time.  They need to feel safe enough to venture out and feed.  Aggressive fish like triggers, dottybacks and aggressive damsels should be avoided.  While tangs would be suitable, large angelfish, the more aggressive dwarf angelfish and all of the pygmy angels would be too aggressive.  Do not house with predatorial fish or eels known to eat small fish, since their small size will result in a short stay in your tank!  There is not a lot of information on housing these with their own kind or within the genus, however, following the cue from all OTHER gobies, only one per tank, unless tank is 4 feet long possibly, providing about 2 feet of room per fish so they have their own sandy/cave areas.  Do not house with larger gobies like the Watchman Goby or sand sifting gobies since they are known to attack other bottom dwelling gobies.  These larger gobies do not appreciate the intrusion and competition for space and food.  Please comment below if you have had success with this fish and other bottom dwelling gobies long term, as in 4 months or more, or when all are of adult size.

Tank should have a sandy bottom that is at least 2” deep, and the tank size needs to be at least 10 gallons (38 liters).  This size is based on other sand dwelling gobies of similar size, which are on record.  Natural algae growth on rocks will also supplement their diet since it will house copepods and other yummy tidbits.  Some from this genus eat benthic algae and other plants, so providing those foods is a good nutritional need to cover just in case.  The temperatures they are found in are 72˚ to 79˚F (22˚-27˚C) and normal pH of 8.0 to 8.3 would help them adjust well.  

For more Information on keeping this fish see:
Guide to a Happy, Healthy Marine Aquarium

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Perciformes
  • Family: Gobiidae
  • Genus: Coryphopterus
  • Species: glaucofraenum
Cave Goby – Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Aquarium Hardiness: Very Hardy
  • Minimum Tank Size: 10 gal (38 L)
  • Size of fish – inches: 3.0 inches (7.62 cm)
  • Temperament: Peaceful
  • Temperature: 72.0 to 79.0° F (22.2 to 26.1&deg C)
  • Range ph: 8.0-8.3
  • Diet Type: Unknown
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Habitat: Distribution / Background

The Bridled or Colon-tail Goby, Coryphopterus glaucofraenum, was first described by Gill in 1863.  The only common name is Bridled Goby, however, one researcher points out that this goby, which is VERY similar to other sand gobies in this genus, has a very distinct colon shape at the base of the tail.  It can be lighter brown to almost black. The term “bridled” refers to the multiple lines on the sides of their face, however many species have this feature, making is very hard to distinguish between them, based on that description alone.   Several online retailers have used the name Transparent Cave Goby and Cave Goby, which pretty much describes all the fish in this genus!

Distribution – Habitat:
The Bridled Goby is found in the Western Atlantic from North Carolina, USA to Bermuda , Santa Catarina, Brazil and the entire Caribbean Sea.  They inhabit burrows in the sand that are both inshore over silty mangroves and turbid waters or in shallow bays with mixed sand and reef habitats.  They are occasionally found on offshore patch reefs or deeper habitats, and range from depths of 6 to 150 feet (2 to 45 m), however most are found in shallower waters.   Males will guard the eggs in the burrow.  Foods are not listed on fishbase, however, taking a cue from other gobies in this genus, Coryphopterus, they may ingest benthic plants and weeds, but they will eat any zooplankton and other planktonic inverts that float by. 

Species Variations and Similar Species:

Sand Goby (C. tortugae):  The Sand Goby’s “eye bar” goes past the pectoral fin and ends at the back dorsal fin or further, has an incomplete upper eye stripe, and does not have the “:” colon shape at the base of the tail.’’

Sand-Canyon Goby (C. bol):  Has a faint bar at the base of the tail, but does not form the rounded “:” colon shape.  It also lacks a dark spot at the lower part of where the pectoral fin meets the body.  This is the only species that lacks the color there.

Pallid Goby (C. Eidolon):  No under-eye stripe, darker specimens have a spot or stripe at the base of the lower part of the pectoral fin. 

Colon Goby (C dicrus):  Lacks the black bars radiating from the iris, but instead forms spots over a darker iris coloring.  It also has a vertical black tail fin bar that doesn’t form the rounded spots of a colon shape.  Oddly, it currently holds the name Colon Goby.

Venezuelan Sand Goby (C. Venezuelae):  Does have the colon shape bar at the base of the tail, however, it also has a sharply outlined dark spot a the lower part of the pectoral fin where it hits the body, instead of just speckling or shading that the Bridled/Colon-tail Goby has. 

  • Scientific Name: Coryphopterus glaucofraenum
  • Social Grouping: Unknown – May be single until spawning.
  • IUCN Red List: NE – Not Evaluated or not listed


The Bridled Goby adults that are found on white sandy bottoms are pale with two rows of faint yellow spots on the body, along with orange and iridescent blue and white spots.  Darker “x” shaped accents can form on the sides of adults in some specimens.   They have a partial horizontal orange “eye bar” streak that runs from the middle of the eye, horizontally and stops near the pectoral fin.  This eye bar can sometimes be underlined in black, making it appear brown to black in some lighting.  Behind the eye, there is a ow of white spots, with the second spot positioned higher than the rest.  None of the other species has this trait.  They also have a row of dusky spots that runs along the entire top of their back. 

Fish from darker substrates, where the water’s turbulence makes for murkiness, have darker pigment with 2 rows of brown o dark brown spots or “x” shaped markings that run down the entire length of the fish, on both sides of the body.  They also have dusky fins and both color morphs have a colon or “:” shape at the base of their tail fin in light brown to almost black, depending on the age and color morph.  The dark color morph also has the partial horizontal orange with possible brown or black accented streak that runs from the middle of the eye and ends at the front of the pectoral fin.  The oversized pectoral fins, which they use to perch on are notched. Typical of a goby, the Bridled Goby lacks a swim bladder and is a sedentary fish, happy to hang out at the bottom of the tank.  

Juveniles often lack some of these marks and it’s true species identification will not be recognized until adulthood.  Males who are in spawning mode are uniformly dusky and are hard to identify.  They only reach 3” (8 cm) and they probably only live around 4 years like most gobies.

  • Size of fish – inches: 3.0 inches (7.62 cm) – 3″ (8 cm)
  • Lifespan: 4 years – They probably only live around 3 to 5 years like most small gobies.

Fish Keeping Difficulty

The Bridled Goby is easy to care for, and is suitable for a reef or fish only system with peaceful tank mates.  Nano tanks will also supply them with enough room since they do not venture far from their burrow.  If there are other sand dwelling gobies, the tank should be at least 4’ long, giving each goby at least 2 feet of space between them to discourage squabbling, unless it is a large shrimp goby or a Watchman Goby.  They should be given a varied died of crustacean flesh, mysis, brine shrimp, and offered minced shrimp and scallops and some veggie matter.  

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

The Bridled Goby may be an omnivore or a carnivore.  There isn’t much in the way of evidence as to stomach contents by ichthyologists as of yet, however others in this genus are known to be omnivores, while some only eat zooplankton.  That being said, offer both items, make observations and share with us below!  Offer frozen/thawed mysis, fortified brine shrimp, mince raw table shrimp and other seafoods.  Also, offer flake and very small sinking pellets on occasion.  Provide some areas of the tank with natural algae which not only may be a food they need, but also can house the copepods and other inverts they enjoy.  It is possible that the fish which had benthic algae and weeds in it’s stomach could have been ingesting that substance while feeding on the inverts hiding in those plants.  Hard to say, but provide some veggies to cover the bases.  Feed twice daily.

  • Diet Type: Unknown – No record of stomach contents. May be a carnivore or omnivore. Provide some veggie material in foods like flake or tablet.
  • Flake Food: Occasionally – Offer flakes for omnivores to cover all bases.
  • Tablet / Pellet: – Offer flakes for omnivores to cover all bases.
  • Vegetable Food: Some of Diet – Possibly an omnivore that takes in limited amounts of algal foods.
  • Meaty Food: Most of Diet – May be an omnivore or carnivore.
  • Feeding Frequency: Several feedings per day

Aquarium Care

Reef tanks:
-Nano/Small tanks up to 40 gallons, perform 5% water changes weekly.
-Medium sized up to 90 gallons, perform 15% bi-weekly. 
-Large Tanks 100 gallons and over, once water is aged and stable can be changed 10% bi-weekly to 20% monthly, depending on bioload.

Fish only tanks:*
Small tanks up to 40 gallons, perform 15% water changes bi-weekly.
-Medium sized up to 90 gallons, perform 20% to 30% monthly depending on bioload. 
-Large Tanks 100 gallons and over, once water is aged and stable can be changed 20% to 30% every 6 weeks depending on bioload.

For more information on maintaining a saltwater aquarium see: Saltwater Aquarium Basics: Maintenance. A reef tank will require specialized filtration and lighting equipment. Regular water changes done  bi-weekly will help replace the trace elements that the fish and corals use up.  Learn more about reef keeping see: Mini Reef Aquarium Basics.

*Note:  If this is the ONLY fish in the tank, with no corals or other fish you can get away 20% monthly.

  • Water Changes: Bi-weekly

Aquarium Setup

A minimum tank size of 10 gallons (38 liters) is suggested, or 20 gallons for a male and female pair.  Provide them with live rock and sand since they are burrowers.  Offer your Bridled or Colon-tail Goby a handful of crushed coral to build with, if they seem to be having a hard time keeping their burrow open.  Any kind of lighting may be used and the temperature span is a little lower than allowed for most tropical marine fish, only being 72 to 79˚F (22 to 27˚C).  The temperature, specific gravity of 1.023 to 1.025 and from pH 8.0 to 8.3 should remain stable.  A gentle to moderate water flow across the substrate will help send food towards their preferred hideout.  It is unknown how juveniles behave and the same can be said of the adults.  If attempting more than one, use the basics from other sand dwelling gobies.

  • Minimum Tank Size: 10 gal (38 L) – 10 gallons (38 liters)
  • Suitable for Nano Tank: Yes
  • Live Rock Requirement: Typical Amount
  • Substrate Type: Sand – They need to burrow, so sand is suggested.
  • Lighting Needs: Any
  • Temperature: 72.0 to 79.0° F (22.2 to 26.1&deg C) – 72˚ F (22˚ C) 79˚F (27˚C)
  • Breeding Temperature: – Unknown, but possibly the warmer end of the temperature range of 79˚F.
  • Specific gravity: 1.023-1.025 SG
  • Range ph: 8.0-8.3
  • Brackish: No
  • Water Movement: Any – They do depend on water flow along the substrate to bring them food.
  • Water Region: Bottom

Social Behaviors

It is unknown if these gobies are compatible with their own kind.  If there is a male and female pair, then they should be fine together.  Obtaining several juveniles and watching to see if any pair up may be a way to achieve this, however have an extra tank for any fish that needs to be removed.  

When it comes to compatibility with other gobies, again, there is not much information.  The Bridled Goby is very peaceful, however, when alone, so are Watchman and Shrimp Gobies.  Add another sand dwelling goby into a tank with that Watchman or Shrimp Goby, and they will go after any it, so caution is needed when adding any other bottom dwelling fish or gobies.  The Bridled Goby is the one that is most likely going to be attacked in that scenario.  House with peaceful fish.  Semi-aggressive fish like tangs and anthias who do not inhabit the lower areas of the tank should be fine.  Certain damsels that are peaceful and like to burrow will be a risk since they are territorial, although most chromis that dwell in the upper levels, such as Blue Green Chromis or Blue Reef Chromis will not bother your sand Goby.  Do not house with anything but the most peaceful dwarf angelfish like the Coral Beauty.  Avoid triggers and large angelfish who will harass them, as well as large wrasses like large Thalassoma that can swallow them whole.  Avoid any predatory fish or large eels for that matter.  The Marine Betta, once full grown will pose a threat, even though this fish is peaceful with fish it cannot swallow! 

The Bridled Goby will not bother any corals

They are invert safe, except for a few copepods here and there

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Sometimes – Only as a known male/female pair.
    • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Monitor – Monitor other sand dwelling gobies for aggression.
    • Semi-Aggressive (anthias, clownfish, dwarf angels): Monitor – Avoid pygmy angels and any dwarf angelfish that are more aggressive than the Coral Beauty.
    • Monitor – Upper tank dwelling Green and Blue Reef Chromis should be okay. Dottybacks and line wrasses are too aggressive.

    • Large Semi-Aggressive (tangs, large angels, large wrasses): Monitor – Tangs should be okay and Halichoeres wrasses shouldn’t bother them. Avoid large Thalassoma who may eat them and the Bird wrasse who is too energetic and will scare the goby into hiding.
    • Large Aggressive, Predatory (lionfish, groupers, soapfish): Threat – These gobies are “bite size” afternoon snacks!
    • Safe
    • Anemones: Safe
    • Mushroom Anemones – Corallimorphs: Safe
    • LPS corals: Safe
    • SPS corals: Safe
    • Gorgonians, Sea Fans: Safe
    • Leather Corals: Safe
    • Soft Corals (xenias, tree corals): Safe
    • Star Polyps, Organ Pipe Coral: Safe
    • Zoanthids – Button Polyps, Sea Mats: Safe
    • Sponges, Tunicates: Safe
    • Shrimps, Crabs, Snails: Safe
    • Starfish: Safe
    • Feather Dusters, Bristle Worms, Flatworms: Safe
    • Clams, Scallops, Oysters: Safe
    • Copepods, Amphipods, Mini Brittle Stars: Safe

Sex: Sexual differences

Unknown, however the male guards the nest.

Breeding / Reproduction

Very little is known, however they probably breed in the summer months in the waters off the east coast of the United States, and then more often in the tropical waters of the Caribbean.  The male turns a dark uniform dusky color when spawning, then female lays the eggs in a burrow and the male guards them until they hatch.  

  • Ease of Breeding: Unknown

Fish Diseases

Unknown, although with poor water quality, they would be susceptible to most marine illnesses.

For more information see Fish diseases.


Becoming more available and the prices are reasonable, however, identity will remain an issue until this goby is studied further. 


Animal-World References: Marine and Reef

Family Gobiidae
Western Atlantic Coryphopterus gobies
By Benjamin Victor
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Coryphopterus glaucofraenum
by Bob Goemans

 Fusigobius signipinnis (Image Credit: Jim Greenfield, Wikimedia Commons CC BY-SA 3.0 Unported)