There's a Dragon in my Tank!

by "Pufferpunk" ( aka Jeni C. Tyrell)

 

There are a few creatures that are claimed to be “so ugly, they’re cute” or “so ugly, only it’s mother could love it”.  This dragon is not quite the same. The Dragon Goby is a gentle monster--it's nowhere close to as mean and evil as it looks. Though it looks like a vicious predator, it's really the opposite.

You cannot help but notice its weird appearance--unlike any fish I know.  Its tiny eyes, huge mouth and long dragon-like dorsal fin set it apart from all other fishes.  A lot of folks would call this fish ugly but I find it very lovely. It is the largest goby in the Caribbean and the only one with this distinctive eel-like shape.  Yes, it looks like an eel with tiny, beady eyes that rest near the top of it’s big head and a large mouth, lined with sharp teeth. This fish also has a beautiful bluish/pink metallic sheen to it, and a long, undulating dorsal fin, closely resembling the serrated back on mythical dragons (hence the “Dragon” name).  I’ve always compared it to the monster that pops out of that poor fella’s chest, then slithers away, in the movie, Alien.  Now that one is ugly!

Meet The Dragon Goby:

(Also Known as The Dragon Eel or Violet Goby)

Scientific name: Gobioides broussonetti

Distribution: Western Atlantic: from Charleston, South Carolina southward to Florida, along the Gulf of Mexico coasts of Alabama, Mississippi, Louisiana, and eastern-central Texas; along the Caribbean coast of Colombia, eastward to Venezuela, Surinam, Guyana, French Guiana, and Brazil as far south as Rio Grande do Sul, Brazil. 

Size: Generally they grow to around 15”-18” but fish as large as 2’ have been found, if kept in a large enough tank.

Water Conditions: Brackish water conditions.  Specific gravity around 1.005-1.010.

Food:  They will eat bloodworms, Cyclops, Tubifex worms, brine shrimps, Daphnia, chopped worms, fish and shrimp, and any other similar food. They will also eat algae wafers, algae and small sinking pellets of fish food.

Recommended Temperature: 73 to 77F, 23 to 25C, a little cooler than most tropical fish.

Although they are not particular about pH, these fish must be kept in brackish water! You must use marine salt and measure it with a hydrometer or refractometer. 

Its normal habitat is mud-bottomed areas in river mouths, estuaries, salt marshes and even the ocean down to 100ft deep.  They may enter fresh water occasionally but are healthiest in brackish water and that is how they should be maintained if they are to thrive.  Keeping it in freshwater will compromise its immune system, causing disease and early death.  The first one I had was kept in fresh water (before I knew better).  It did live to 5 years.  At around 2 years, it started to develop pink tumors all over its body.  By 5, it had developed one inside its mouth, until it could not close its mouth anymore.  Since they are filter feeders, they must be able to close their mouth after gulping in food and water.

They are mainly scavengers who put forth only minor effort in searching for food.  Their primary method of obtaining food is by scooping up mouthfuls of sand and sorting the edible things from the substrate, then they spit out the substrate and swallow the food particles. They also use their lateral “chin fin”, to dig around the substrate.   It feeds on diatoms (the brown algae so common in aquariums), various sea algae, small shrimp and anything else that can fit in its mouth, EXCEPT fish. They thrive on Wardley Shrimp Pellets.  Mine has been known to suck on an algae wafer until it gets soft and then gulp it down.   Dragons have tiny eyes and extremely poor vision.  They generally hide all day and come out at night to feed.  Since it can’t see or swim very well, the number one cause of death of these fish is starvation.  Do not keep with more aggressive eaters, as it often has difficulty finding food before the other fish in their aquarium have eaten all of the food.   It is best to drop their food near the opening of their cave, after lights out. Since they have been observed in the wild to eat continuously, it would be best to meter out several small feedings throughout the day. Do not overfeed and clean up any uneaten food.  Lacking the normal fish’s swim bladder, they are poor swimmers and wiggle back and forth like a snake in the water or scoot along the substrate and rocks on their lateral fin.  Sometimes you can see them standing vertically on their pectoral fin, sticking to the glass by their ventral fin.

A sandy substrate is best for them to dig around in.  Sharp rocks can injure the fish.  They will create a burrow under or behind a large rock. Being quite shy, dragon gobies like to hide in caves but the caves need to be small because they seem to prefer tight fitting places. PVC pipe will do well also. A large open cave in full view will simply cause the goby to burrow next to the farthest side.  You can trick them by leaning a flat rock against the front glass. They’ll move into their new cave and stay right out front.  They will chase out other fish that try to barge in on their territory.  With a heavily decorated tank, they will feel secure enough to come out more often during the daytime.  Live plants do not do well in brackish water.  You could try java fern or java moss but plastic or silk plants are recommended.

Most aquarium shops and even many books have stated that these fish are fierce predators. Despite its aggressive reputation it is a very peaceful fish and won't harm smaller fish.   They have been known to squabble amongst themselves but it is ok to keep them with conspecifics, as long as there is enough room. Dragon fish are best kept singly, unless a large group can be kept in a tank of about 100 gallons or more. In small tanks or small groups, one larger Dragon Goby will dominate the others and some may be bullied or not get enough food.  You can keep them with other brackish water gobies, like Bumblebee Gobies or Knight Gobies.  It cannot compete with aggressive or boisterous tankmates.

Since these are scaleless fish, Dragons are more prone to skin diseases.  They are also more sensitive to medications, so the best preventative to disease is a clean tank.  Good filtration and weekly water changes will help keep their water conditions pristine.  They must be introduced into a fully cycled tank. If purchased in freshwater, cycle the tank as freshwater and slowly bring the goby’s specific gravity up .002/week, until you have reached your desired SG.

Sexual dimorphism of G. broussoneti is distinguished by a small urogenital papilla, which is in the ventral region between the anal opening and the anal fin. In the females it is short, blunt and has a yellow coloration; in males it is thin, pointed and has a smooth appearance.  Spawning is possible in a large aquarium. Harper, in Tropical Fish Hobbyist (#473), documents success in captive spawning on pages 130-132. He suggests using a spawning group of one male and three or more females. The tank should be furnished with hiding places for the females and as a nest for the male. The fish should not be fed for a week and then conditioned on live foods. The salinity should be lowered and then raised. The male will spawn with several females over the course of a day. Following spawning, the females should be removed and the male will guard the eggs. After 36-48 hours, the fry hatch and the male should be removed. After the egg sacs are consumed, the fry can be fed roftiers and green water containing algae. After a month, Artemia nauplii can be fed. (For more information, please check the article in TFH). There are no other spawnings in captivity that has been reported. Questions about reproductive seasonality, ovarian development and spawning of G. broussoneti need further investigation.

This is not a fish for beginner aquarists or even experienced freshwater aquarists beginning in brackish water. A lot of these are sold because of their odd appearance and common names. Who wouldn't want a purple dragon? But that is insufficient reason to buy a fish and a lot of these animals are kept inadequately, as is the case with most brackish species.  Too many aquarium shops tell folks to just “add a little aquarium salt” to make your tank brackish. You need to be dedicated to keep this goby, making sure to keep their water very clean and that they are eating well.  If kept properly, this exotic, unusual fish can live close to its teens. All in all, this is a fascinating, beautiful oddball, for an advanced aquarist to keep in his or her brackish tank.

P.S. You can visit Jen's website at: www.thepufferforum.com