How to Care for a Violet Goby (Dragonfish)
A violet goby, or Gobioides broussonnetii, is sometimes called the dragon goby or erroneously called a dragonfish (the name of the arowana among other fish). It prefers brackish water and is native to the swamp waters around Florida and the Gulf of Mexico.
The violet goby is a long, slender fish that resemble an eel (but is definitely not an eel!) and have a silvery gold iridescence to the skin.They can reach lengths over two feet in the wild. The dragon goby has ventral fins that allow them to cling to the walls of the aquarium. Their dorsal fin runs almost the entire length of their bodies.
Dragonfish are carnivores and mistakenly labeled as aggressive fish. But, ironically, these fish are the ones that get bullied. They are not aggressive at all, preferring to hide in the sand, behind rocks, and under plants.
Their teeth are very sharp. But in the wild, they use them to scrape algae off the rocks in their environment. They don't use them to fight other fish. These fish are scavengers and typically scoop up large mouthfuls of substrate and sift through it for edible material, spitting out the substrate and eating the food. They also have large gills that allow them to filter and expel sand.
Your Dragonfish Tank
The violet goby needs lots of space. A good rule of thumb is 25 gallons for each specimen. It is recommended that you start with 50 gallons at the minimum. The tank should also be at least four feet in length.
These fish are territorial when it comes to living with other dragon gobies, so it's a good idea to have a six-foot aquarium for two of them and larger aquariums for multiple gobies.
In the wild, these fish can grow up to 24 inches long; however, they rarely grow any larger than 15 inches when kept in an aquarium.
Substrate and Plants
The floor of their new home should be a sand substrate because they like to bury themselves in it. Rocks can cause injuries to their fins, leading to infection and possibly death.
They also need a lot of hiding places. Plants, logs, caves, anything they can back themselves into will provide much-needed shelter. Dragon gobies enjoy a variety of plants including:
- Marimo Balls
- Java Moss
- Java Fern
When selecting plants, keep in mind that these fish can easily uproot plants that are not secured above the substrate level. Be sure to protect any plants from possible digging.
Water Type and Temperature
Dragon gobies also need very clean brackish water. It is best to change 10 to 15 percent of the water every week and keep up on any maintenance your filter may require. You will also need a water heater and thermometer.
Dragonfish prefer temperatures between 77° and 82° F, the ideal temperature being 80 F. Our dragon goby seems to prefer 78° F, however. The pH should be kept between 6.5 and 8.5. Ammonia levels also need to be kept low, these fish have a high sensitivity to ammonia. It will cause the fish to scramble to the surface and gasp for air. If not diluted quickly, the ammonia will kill the dragonfish.
Have You Ever Owned, or Do You Own a Dragonfish?
Feeding a Violet Goby
These are hearty fish and tend to be scavengers, sifting through the sand to find algae and other small organisms. In the aquarium setting, gobies will eat frozen black tubiflex and blood worms along with sinking shrimp pellets.
They have very small throats, so anything they eat must be very small. Algae wafers and flake food can also be on the menu. Our dragon goby dislikes flake food and much prefers algae wafers.
It should be noted that dragonfish may not eat for the first one to two days after you introduce them to their new home. After they have acclimated, they should be fed once a day and only fed as much food as they can consume within two minutes.
These fish are shy and nocturnal, preferring to be active at night, which can give the owner quite a scare. They do adapt to feeding during the day, however, and do so rather quickly.
Keeping Dragon Gobies With Other Fish
Violet gobies should not be in a tank with aggressive fish such as oscars and tiger barbs. Oftentimes, the dragon gobi will become the victim of fish bullying, so it is best to keep them with smaller, non-aggressive fish. However, very small fish may become dinner for the dragon goby.
Medium sized fish that are tolerant to brackish water make the best companions:
- Knight Gobies
- Orange Chromides
- Bumblebee Goby
- Celebes Rainbowfish
It is important to note that these fish have very small eyes, and are almost blind. This makes it difficult for them to compete with other fish for food. They find their meals using their sense of smell rather than sight.
Adding fish to help keep the tank clean will keep your Violet Goby healthy and minimize some of the cleaning you'll need to do. The best choices for this are amano shrimp, nerite snails, and ghost shrimp.
Requirements for a Dragon Goby Aquarium
50 gallons minimum
Live aquatic invertebrates
25 gallons per Dragon Goby Fish
Freeze dried bloodworms
pH between 6.5 and 8.5
Low ammonia levels
Aquarium Sand Substrate
Lots of variety in their diet
Temperature between 77 and 82 degrees
Lots of hiding places
Dragonfish are hardy animals, but like everything else, they can be susceptible to some illnesses. They are most commonly affected by bacterial infections such as fin rot or Columnaris.
Fin rot causes a fraying of the fin edges which also turn black. The disease progresses until it reaches the base of the fin and is a result of a bacterial or fungal infection.
The bacteria Pseudomonas fluorescens causes the fins to rot in a ragged fashion. It can also be caused by a fungal infection which typically causes the fins to rot in a more even way. The fungal version also causes a white edge on the fin. Both fungal and bacterial fin rot can affect the fish at the same time.
The fungal version also causes a white edge on the fin. Both fungal and bacterial fin rot can affect the fish at the same time.
Fin rot is typically caused by:
- Poor Water Conditions
- Poor Diet
It can also be a secondary infection in a fish that is already suffering from a primary disease that is causing stress.
Columnaris (also known as cottonmouth) is caused by Flavobacterium columnare which is a rod-shaped bacterium that is gram-negative and aerobic. It is much more virulent than fin rot but can mimic it in the initial stages causing a ragged fraying of the fins.
The skin of the fish will begin to appear ulcerated within 24 to 48 hours which is followed by loss of the epidermal layer and then eventually cloudy or white colored patches that resemble the appearance of fungus.
These patches typically manifest in the filaments of the gills along with mucous which can also appear on the dorsal regions and head. The gills may begin to necrose, changing color to a light or dark brown and then black (the final stage of necrosis).
The most common symptoms of Columnaris include:
- Rapid and Labored Breathing (caused by damage to the gills)
- Rubbing the body against objects
- Inflammation around the infected areas
- Death (typically within 48 to 72 hours unless treated)
Both fin rot and Columnaris are treatable, although fin rot has a better prognosis. Both diseases can be treated with antibiotics (or an anti-fungal in the case of fungal fin rot) and the temperature of the tank should be lowered to about 75°F to minimize virulence.
Dragonfish Fights a Snail for an Algae Wafer
Buying Your Dragonfish
If you purchase your dragon gobi from a reputable pet shop, they should already be kept in brackish water. Make sure to ask what type of water they are being kept in so that you can prepare your tank before bringing the fish home.
Fish kept in stores like Walmart or large chain pet stores are typically kept in fresh water because it's easier to maintain. These fish can do well in fresh water, and it is possible to transfer them from brackish to fresh with a bit of transition. However, these fish tend to be much healthier in their native, brackish water.
A Word of Caution
These fish are excellent escape artists. If the water quality is not to their liking, they will float on the top of the water, gulp for air, and attempt to leap out of their tank.
I woke up to find my dragonfish nowhere to be found. My daughter said she heard a noise and saw him fall behind the dresser, and sure enough, that’s where I found him. He was about two feet away from his tank! For a small fish, that's a long jump.
I’m not sure how long he was there, but he was actually still alive. We have since changed the hood on his tank, and he has earned the name “Fumbles."
A Personal Note
Unfortunately, when we bought our violet goby, we weren't told any of the above information. The pictures you see in this article were taken as we were setting up the tank and before its completion. Our fish was quite active during this time so it was easy to get pictures. But as you can see, we started with rocks instead of sand, and didn't have a lot of places for him to hide.
If you decide that this fish is right for you, don't buy it from Walmart like we did, and if you do, make sure you research this beautiful creature as much as possible before you bring it home. They really are a beautiful, but they do require maintenance and a very specific environment. They are also very hearty fish, and tolerate change well if it's done slowly.
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Questions & Answers
© 2013 Melissa Flagg COA OSC