Violet goby
The violet goby is a species of goby native to marine, fresh and brackish waters near the Atlantic coast of North and South America from South Carolina in the United States, to northern Brazil. It prefers bays, estuaries and river mouths with muddy substrates. It is found in the aquarium trade, where it is often marketed as dragon goby or dragon fish.
Description
The violet goby has a long, slender, eel-like body. Its dorsal and anal fins run almost the entire length of the body. The teeth are very sharp; however these are used for scraping algae off rocks, not fighting. When kept in good condition, dragon gobies develop an attractive, iridescent, silvery-blue metallic color with a gold blotch pattern. Violet gobies seen in pet stores are generally long. In the wild, violet gobies can grow to long. However, in captivity they seldom grow past. Males tend to have long, pointed genital papilla, while that of the females are shorter, blunt, and yellow in color.Habitat and feeding
Violet gobies usually inhabit brackish swamps, streams, and estuaries with a muddy substrate. They have very small eyes, and as such are primarily scavengers.Aquarium care
Its commercial trade name is "dragon goby" or "dragon fish". Information offered in pet stores is often misleading; this species has specialized requirements and will die in a standard aquarium. Violet gobies require brackish water at least one-quarter the strength of seawater. A single individual needs a tank at least four feet long with a floor of sand or silt at least three inches thick. They are territorial with their own kind and cannot be kept together in a standard-sized tank. They cannot compete with common aquarium fish such as tetras and barbs and are unsuitable for a community tank. Individuals are usually wild-caught, and may have trouble learning to eat commercial fish foods. They feed mostly on filamentous algae, and in captivity must have access to vegetable food such as spirulina flakes or algae wafers. It is often sold as a "highly aggressive" fish, but violet gobies are actually quite docile, and nearly blind.Popularity, availability, and hardiness
This is not a very common fish among hobbyists, perhaps because it is hard to find, both commercially and in the tank. Dragon gobies tend to disappear from the market for long periods of time, but are easier to find in stores within their natural range. Meanwhile, they often hide all day, coming out only when the lights are out and owners asleep. As noted above, they are often described by local fish stores as aggressive, capable of eating any fish that fits in their mouth, when in fact they are scavengers.Behaviour and aggression in captivity
Despite its fierce looks, large mouth, and many teeth, the violet goby is a predator-scavenger. If well fed, it usually will not bother smaller fish. Any small, peaceful, brackish water-tolerant fish can coexist with violet gobies, so examples include mollies, guppies, swordtails, platies, bumblebee gobies and glassfishes. The violet goby is only kept with peaceful fish, as it has poor eyesight and may be bullied by more boisterous fish.However, if two violet gobies exist in a tank too small, one will eventually claim the entire area their own territory and fiercely defend it.