Batasio

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Batasio
Batasio fasciolatus.jpg
Batasio fasciolatus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Siluriformes
Family: Bagridae
Genus: Batasio
Blyth, 1860

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.

Taxonomy[edit]

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 tentativelly placed in Batasio, but its generic placement is questionable.[2][3]

Species[edit]

There are currently 18 recognized species in this genus:

Distribution[edit]

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]

Appearance and anatomy[edit]

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]

Ecology[edit]

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]

In the aquarium[edit]

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]

References[edit]

  1. ^ Froese, Rainer, and Daniel Pauly, eds. (2015). Species of Batasio in FishBase. October 2015 version.
  2. ^ a b c d e f Ng, H.H. (2004). "Batasio elongatus, a new species of bagrid catfish from southwest Myanmar (Siluriformes: Bagridae)" (PDF). Ichthyological Exploration of Freshwaters, 15 (1): 67–70. 
  3. ^ a b c Ng, H.H. & Edds, D.R. (2004). "Batasio macronotus, a new species of bagrid catfish from Nepal (Teleostei: Bagridae)" (PDF). Ichthyological Exploration of Freshwaters, 15 (4): 295–300. 
  4. ^ Darshan, A., Anganthoibi, N. & Vishwanath, W. (2011). "Batasio convexirostrum, a new species of catfish (Teleostei: Bagridae) from Koladyne basin, India" (PDF). Zootaxa, 2901: 52–58. 
  5. ^ a b c d e f g h i j k Ng, H.H. (2006). "The identity of Batasio tengana (Hamilton, 1822), with the description of two new species of Batasio from north-eastern India (Teleostei: Bagridae)". Journal of Fish Biology, 68 (Suppl. A): 101–118. 
  6. ^ Ng, H.H. & Kottelat, M. (2008). "Batasio feruminatus, a new species of bagrid catfish from Myanmar (Siluriformes: Bagridae), with notes on the identity of B. affinis and B. fluviatilis". Ichthyological Exploration of Freshwaters, 18 (4): 289–300. 
  7. ^ Plamoottil, M. (2015). "Batasio flavus, a new catfish species (Siluriformes: Bagridae) from Kerala, India" (PDF). Journal of Research in Biology, 5 (5): 1799–1808. 
  8. ^ Ng, H.H. (2008). "Batasio procerus, a new species of catfish from northern Myanmar (Siluriformes: Bagridae)". Ichthyological Exploration of Freshwaters, 19 (1): 1–6. 
  9. ^ a b c d e f g h i Bhatt, A. & Jayaram, K.C. (2004). "A New Species of the Genus Batasio Blyth (Siluriformes: Bagridae) from Sharavati River, Uttara Kannada, Karnataka" (PDF). Zoos' Print Journal, 19 (2): 1339–1342. Archived from the original (PDF) on 2009-10-25. 
  10. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio affinis" in FishBase. October 2015 version.
  11. ^ a b c Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio fluviatilis" in FishBase. October 2015 version.
  12. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio tigrinus" in FishBase. October 2015 version.
  13. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio dayi" in FishBase. October 2015 version.
  14. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio pakistanicus" in FishBase. October 2015 version.
  15. ^ a b c d e f g h i j k Linder, R.S. (2000). "The Catfishes of Asia Family Bagridae part one" (PDF). Cat Chat, 1 (1). 
  16. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio tengana" in FishBase. October 2015 version.
  17. ^ Froese, Rainer and Pauly, Daniel, eds. (2015). "Batasio travancoria" in FishBase. October 2015 version.