| Batasio | |
|---|---|
 | |
| Batasio fasciolatus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Siluriformes |
| Family: | Bagridae |
| Genus: | Batasio Blyth, 1860 |
| Type species | |
| Pimelodus batasio F. Hamilton, 1822 | |
Batasio is a genus of catfish of the family Bagridae. These small fish are found in fast-flowing hillstreams throughout South and mainland Southeast Asia.
Batasio was first described by Edward Blyth in 1860 with Batasio buchanani (a needless renaming of Batasio batasio) designated as type. [1] B. pakistanicus, described in 1989, is tentatively placed in Batasio, but its generic placement is questionable. [2] [3]
There are currently 18 recognized species in this genus:
Batasio species are generally found throughout South and mainland Southeast Asia. [2] B. affinis is found in Myanmar. [10] B. fluviatilis is found in Northern Malay Peninsula. [11] B. tigrinus is also recorded from Thailand. [12] B. dayi originates from the Salween and Irrawaddy River drainages in Myanmar. [13] B. elongatus is found in southwestern Myanmar. [2] B. macronotus originates from eastern Nepal. [3] B. pakistanicus is found in the Indus River. [14] B. batasio also originates from northern India where it shares its habitat with Mystus vittatus . [15] B. fasciolatus is known from the Tista River drainage, a tributary of the Brahmaputra River. [5] B. merianiensis is found in the Brahmaputra River drainage. [5] B. sharavatiensis originates from the Sharavati River in Uttara Kannada, Karnataka. [9] B. spilurus is known from the Brahmaputra River drainage in the vicinity of Dibrugarh. [5] B. tengana is known from the Ganges and the Brahmaputra River drainages; it is apparently restricted to upper reaches of larger rivers. [5] B. travancoria is distributed in the Chittar, Kallada and Pamba Rivers in southern Kerala and is considered a rare species. [9]
Batasio species typically have enlarged sensory pores on their head, laterally compressed heads and bodies, and at least 35 vertebrae. [5] B. tengana, B. pakistanicus and B. spilurus differ from other Batasio species in that their adipose fin is much shorter. [5] These fish are small catfish. [2] B. pakistanicus and B. spilurus are the smallest species, reaching only 35 millimetres (1.4 in) SL and 45 mm (1.8 in) SL respectively. [5] The other species range from 55–101 mm (2.2–4.0 in) SL. [5]
B. affinis, B. dayi, and B. fluviatilis have bars or bands, spots or stripes, and are not plain-bodied. [9] B. pakistanicus has a black humeral spot with a dark streak on the dorsum. [9] B. batasio has a dark stripe along the lateral line and another above. [9] B. batasio does not exceed 10 centimetres (4 in). [15] B. fasciolatus and B. tigrinus are the only Batasio species in which the adult colouration consists of five or six vertical dark brown bars on a light brown body. [5] B. tengana has bands descending from the dorsal surface to the lateral line. [9] B. travancoria has a lateral stripe along the lateral line and a faint shoulder spot. [9] B. sharavatiensis is the only Batasio that has a completely plain and colourless body; its adipose fin is almost confluent (continuous) with the caudal fin save for a small notch. [9]
Batasio, like most other bagrids, are easy to sex. The male has a visible genital papilla just fore of the anal fin. [15] Gravid female B. tengana (South East Asian form) are easy to identify because the pink eggs can be seen through their semi-transparent belly when they swim near light. [15]
Batasio species generally are found in fast-flowing hillstreams. [2] B. fluviatilis is found in rivers and streams with moderate to swift current and a predominantly rocky bottom, and is less often in slow-flowing streams with a muddy substrate. [11] B. tengana occurs in rivers and canals and is found in torrential streams. [16] B. travancoria occurs in hillstreams and rivers at the bases of hills. [17] B. fluviatilis hide among stones or submerged vegetation during the day and come out at night to feed. [11] B. batasio appears to mimic Mystus vittatus , with which it inhabits the same habitat. [15]
B. tengana, though uncommon, is the most commonly encountered species of Batasio in the aquarium hobby. [15] B. tengana does well in captivity, and has been bred in captivity. The fish spawned in soft neutral water, but raising the fry, of which there were over 200, proved difficult. [15] The temperature for the Indian species should remain between 20–22 °C (68–72 °F); the Southeast Asian Batasio will tolerate slightly warmer waters. It appears that all Batasio need a lot of current and a high oxygen content. [15]
B. batasio is another species in the hobby, but can be easily confused with Mystus vittatus. [15] B. travancoria has only once been imported to the U.S. [15] In captivity, the experience of one aquarist is that specimens of B. travancoria show little interest in all foods offered and slowly lose weight over a span of a few months and perish. [15]
The Bagridae are a family of catfish that are native to Africa (Bagrus) and Asia from Japan to Borneo. It includes about 245 species. These fish are commonly known as naked catfishes or bagrid catfishes.
Bagrus is a genus of bagrid catfishes. These are relatively large catfish found in freshwater habitats in Africa, except for the virtually unknown B. tucumanus from South America, which likely is a synonym of Luciopimelodus pati.
Hemibagrus wyckioides, the Asian redtail catfish, is a species of catfish of the family Bagridae.
Hemibagrus wyckii is a species of catfish of the family Bagridae. It is occasionally called the crystal-eyed catfish or black devil catfish.
Bagrichthys is a genus of bagrid catfishes.
Hemibagrus is a genus of catfishes of the family Bagridae.
Mystus is a genus of fish in the family Bagridae native to Asia. Phylogenetic relationships within this genus are poorly understood, though it has been suggested that there are two major lineages.
Olyra is a genus of catfishes of the family Bagridae. This genus occurs throughout South Asia and western Indochina, from India to western Thailand.
Leiocassis is a genus of bagrid catfishes found mostly in Southeast Asia with some species occurring in China.
Pseudobagrus is a genus of bagrid catfishes that inhabit streams and rivers throughout East Asia. About half of these species occur in China.
Pseudomystus is a genus of catfishes of the family Bagridae.
Exostoma is a genus of sisorid catfishes native to Asia. These species are distributed in the Brahmaputra drainage of north-eastern India, and east and south to the Salween drainages in Burma. E. berdmorei is found in the Sittang and Salween drainages in Burma. E. labiatum is known from the Brahmaputra drainage in north-eastern India, but has also been recorded in the Salween drainage in Burma, the Ayeyarwady drainage in China, and the Brahmaputra drainage in Tibet and Burma. E. stuarti is from the Ayeyarwady River of Burma and India; however, it has not been collected since its original discovery. E. labiatum is found in mountain rapids.
Mystus vittatus, the striped dwarf catfish, is a species of catfish of the family Bagridae. It is found in brackish water systems with marginal vegetation in lakes and swamps with a mud substrate of Asian countries Pakistan, India, Sri Lanka, Nepal, Bangladesh and probably Myanmar. Populations of Southeast Asian countries is in debate, due to close morphological similarities among Mystus species in that region.
Batasio tigrinus is a species of catfish of the genus Batasio in the family Bagridae, known from Thailand. It is found in the hillstreams of Mae Klong and it was described from Khwae Noi River, one of the main tributaries of Mae Klong; its habitat is sandy/rocky substrate. It is sporadically collected as an ornamental fish; the threats are not well known but may be human disturbance and siltation.
Hemibagrus divaricatus is a species of bagrid catfish found in the Perak River drainage in the western Peninsula of Malaysia. This species reaches a length of 30.8 cm (12.1 in).
Hemibagrus semotus is a species of bagrid catfish found in the Padas River drainage and the shorter coastal rivers which drain the west face of the Crocker Range in northern Borneo, Sabah, Malaysia. This species reaches a length of 19.9 cm (7.8 in).
Hemibagrus lacustrinus is a species of bagrid catfish found in Sumatra, Indonesia in the Danau Singkarak and upper Ombilin River. This species reaches a length of 22.3 cm (8.8 in).
Hemibagrus spilopterus is a species of bagrid catfish from Cambodia, is only known from the lower Mekong. This species reaches a length of 5 cm (2.0 in).
Pseudolaguvia ferruginea is a species of sisorid catfish from the Raidak River, which is a tributary of the Sankosh River, which is in turn a tributary of the Brahmaputra River in India. This species reaches a length of 2.9 cm (1.1 in).