Opsarius
Location. Fishes from the genus "Opsarius" can be found in a variety of countries in South East Asia. These countries include Cambodia, Laos, Thailand, Myanmar, India, and China. Certain species of "Opsarius" are considered endemic to their respective habitats; such as "Opsarius" cocsa and "Opsarius" "maculatus" which are endemic to India. Status. According to the IUCN Red List, significant data is lacking to determine the status of all of the Opsarius species except for "Opsarius koratensis." "Opsarius koratensis" was last evaluated in March of 2011 and was determined to be stable and locally common throughout its range. Habitat deterioration , specifically agriculture, deforestation, pollution, and other ecosystem modifiers, is a possible hazard for these fishes. Habitat. Fishes of the genus "Opsarius" can be found in inland freshwaters such as streams, rivers, creeks, and waterfalls. Generally, these water bodies will have sandy or rocky bottoms which is the preferred benthic environment for these fishes. Fishes of this genus have also been known to live in wetlands. Discovery. The first evidence of "Opsarius" in scientific literature can be found in the book Indian Cyprinidae published in 1839 by John McCleland. In this book many different "Opsarius" species were identified. In the following  years little additional information on this species of fish was collected. Today, there is very little information published on these fishes and new discoveries have not been made in many years. Body Characteristics. Species of the genus "Opsarius" have widely cleft mouths resemblant of carp. Additionally, "Opsarius" species will have a slender body usually marked by transverse stripes or spots. The dorsal fins of "Opsarius" are spineless and small. One of the largest "Opsarius" species is "Opsarius tileo" which grows to 15 cm in length. Diet. Some "Opsarius" species are considered to be fish-eating. Other "Opsarius" species are surface  feeders and primarily will feed on insects. The insects that "Opsarius" species will choose to feed on will be smaller in size as the gape limitation limits "Opsarius" species to what they can fit in their mouths. Human Uses. Humans use the various species of "Opsarius" in a variety of ways. "Opsarius pulchellus" is not considered food, but is used as bait in fence filter traps. "Opsarius pulchellus" also is sold in the aquarium trade internationally. "Opsarius koratensis" is not used by humans as widely as the prior. "Opsarius koratensis" is not used for food, or for fishing, and is  rarely seen in the aquarium trade. "Opsarius tileo" is considered a good table fish, especially in the Eastern Himalayas. "Opsarius tileo" is also found in the aquarium trade. "Opsarius bernatziki" is not used as a food fish but is found in the ornamental fish trade. "Opsarius barna" is not used widely in the aquarium trade. In Nepal, "Opsarius barna" stimulates the economy by being sold as a food fish. "Opsarius barnoides" is not used as a food fish but as an aquarium fish.