Stigmatogobius sadanundio, or the Knight Goby, is a member of the family Gobiidae of the order Perciformes

Perciformes

The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...

. Of the true gobis, Stigmatogobius sadanundio is a very popular, if infrequently imported, goby

Geographical distribution and Habitat

Knight Gobies live in fresh and brackish waters in Borneo

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

, Java

Java

Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...

, Sumatra

Sumatra

Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

, and the Philippines

Philippines

The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

. Knight Gobies are territorial bottom-dwellers, but usually won't bother mid and top level fishes

Physical description

There are two dorsal fins on this gray-blue fish: the first consists of about six stiffly held rays (often with a black blotch); the second is equal in length to the long-based anal fin. Both carry dark spots.

Diet, and feeding behaviour

The Knight Goby prefers live food, but will take most commercially available formulations

Aquarium care

The Knight Goby should be kept singly with other mid-level species. When placed in an aquarium with fish of the same species quarels may arise as this is a very territorial fish. It does best in low light, as bright light makes it skittish. It needs plenty of rocks, caves, and natural territorial boundaries. Good tankmates are swordtails and sailfin mollies.

Temperature, pH, and salinity

The Knight Goby benefits from a fluctuation in temperature over a 24 hour period, with a lower temperature at night. They will tolerate temperatures between 20–26 °C (68–78.8 F). It is not essential, but the fish will do better with 1-2 level teaspoons of salt per 11 litres (2.5 gallons).

Breeding

If you wish to breed them, a species tank is best. The water temperature should be raised to about 24–28 °C (75.2–82.4 F), and the addition of salt helps induce spawning/ A sand substrate is required. The gobies lay their eggs on the ceilings of caves, so an inverted pot makes a good substitute. A pair may produce 1000 or so eggs each of which is attached to the cave ceiling by a fine thread. Both parents tend the brood and the fry are relatively easily reared on newly hatched brine shrimp.