*** originally posted by xaviergal on March 15th, 2007 ***
Scientific name: Gobioides broussonetti .
Distribution: Atlantic coast estuaries from southern United States down to Brazil
Size: at least a foot in the aquarium, up to two feet in the wild
Common names: dragon goby, dragon fish, violet goby
Temperature: 76 to 80 degrees
What at first glance looks like a fierce predator is actually the peaceful, and often misunderstood, Violet Goby. They have a long sleek grayish purple body, over 2 feet in the wild, giving them an eel-like appearance.
Their dorsal fin runs the length of their body with a series of rays. They have a fused ventral fin, a feature of the gobidae species, which they use to prop themselves up on followed by a long anal fin, which like the dorsal fin, runs the length of its body. The violet gobies pectoral fins are round and are used for both swimming and maneuvering on the bottom. Their caudal fin is spade shaped. The violet goby has an under formed swim bladder, as a result they spend most of their time on the aquariums floor rather than in the water column.
While violet gobies can survive in fresh water for short periods of time, a brackish environment is necessary for long term health and happiness. Feeding can be difficult because of their small eyes, vision is very poor, and small throats that prevent a lot of potential fish foods from being consumed.
Given a large enough aquarium more than one violet goby can be kept, however, they are territorial fish amongst their own species so care should be taken in providing adequate caves, pvc pipes, etc.
Since the violet gobies swim bladder prevents it from spending its time in the water column the most important things to consider when setting up a suitable home is to ensure that it has adequate floor space and plenty of places to hide. I would suggest a minimum tank size of 55 gallons for one of these gobies. This will give four feet of tank length for your fish to cruise around on, however, considering these guys get over a foot in the aquarium a larger tank is better if possible.
In the wild violet gobies are filter feeders, they take huge gulps of water and sort through the substrate sifting out food such as algae and small worms or shrimp. The stuff that they don’t eat gets passed through their gills. As a result, a sand substrate is highly recommended. A gravel substrate, especially if it is sharp, can be harmful to their gills during the feeding process. Additionally, sand provides a soft surface for them to rest on.
Due to their poor vision, violet gobies often feel insecure in their environment, especially if there are more boisterous fish around. By adding a few caves and pvc pipes your goby will feel much more comfortable. If you are concerned about not being able to see your fish anymore, construct a cave that is leaning against the front glass, their bad eye sight makes them perceive the glass as a wall. They have their security and you can enjoy them.
While most of their activity does occur at night, I have found that by meeting these housing needs they can be seen daily cruising around at some point
Now for the water, it really does need to be brackish for the long term health and happiness of your fish. Violet gobies are naturally found in estuary zones. These are areas where a river meets the ocean (delta). The salinity of the water is determined by two variables: the strength of the oceans tide and the strength of the rivers flow. If the tide is stronger then the estuary water will be saltier and vice versa. From my experience, violet gobies will thrive with a specific gravity (term used to measure how salty the water is) between 1.006 and 1.008. To make your fresh water brackish you will need marine salt and a hydrometer (used to measure the specific gravity).
Plants are a welcome addition, but you are limited in your options because it’s a brackish environment. Most plants really don’t like salt. With that being said, I have been able to successfully keep java fern, watersprite, and val sp. The watersprite is a great choice for a floating plant and the subdued light will make your violet goby feel more secure in his home.
As with all brackish aquariums, good filtration and routine tank maintenance are a must.
Violet gobies are scavengers in the wild and need a varied diet for optimum health but are limited by two factors, their small throat size and really poor vision. Despite having huge, tooth filled mouths, these fish actually have very small throats and this has to be taken into consideration when purchasing food for them. Frozen blood worms, frozen brine shrimp, frozen mysis shrimp, algae wafers (broken up into smaller pieces), and veggie flakes are all suitable food for them. I would recommend feeding as many of the above as possible on a cycle, ie blood worms one day, algae wafer the next, etc.
Unless they are in a species specific tank, violet gobies often lose in the competition to find food first because they can’t see it. If you find that your goby isn’t getting his fair share of the food try feeding him after lights out, when the rest of the fish are sleeping he will be out looking for the goods =). I have also been successful using a long pvc tube that I position above their heads then drop the food right to them.
My experience has shown that as the violet goby gets more comfortable in their environment they start getting bolder at feeding time. I no longer need to feed after dark nor do I have to drop the food right into their mouths.
More often than not I see violet gobies in tanks with other predators, simply based on their appearances and not their actual behavior. Don’t be fooled by the scary mouth and the “dragon”-like appearance! These fish are as peaceful as they get. As highlighted in the feeding section, they are blind filter feeders. As a result, what looks scary to us is actually an easy target for other predatory fish. I recently purchased two violet gobies that were badly wounded by figure eight puffers. The puffers had completely removed all of their fins, the gobies looked like snakes in the tank
When looking for tank mates make sure that they are classified as peaceful. A fish that fin nips will not appropriate for this tank. I would recommend guppies, mollies, and bumblebee gobies.
They can live in groups provided that the aquarium has adequate running room with plenty of safe spots such as caves. If you are going to have multiple violet gobies try to get ones that are all the same size. Large ones will dominate over smaller ones in territorial disputes.
I am unaware of any successful breeding in the aquarium.
While these fish do have several special needs that need to be taken into consideration, I have nothing but good things to say about them. They have plenty of personality, are quite smart, and really hardy. They are amongst my favourite
If you have any questions please feel free to post in the "all other fish" forum and I will be happy to help
---pics added 02/05/07
here's an image showing the damage that occured over night in a tank shared with figure eight puffers at the LFS. These gobies really are vulnerable to aggressive fish, they just cant see the attack coming.