Nonn Panitvong/Siamensis.org

The Betta splendens-group fish previously known in the hobby as B. sp. ‘Maha Chai’ is officially described in the journal ‘Zootaxa’ this week.

B. mahachaiensisis named for the coastal subdistrict of the Maha Chai in Samut Sakhon province, just south of Bangkok, where it was first discovered, and is notable since unlike other members of the genus it inhabits brackish water habitats and often builds its bubble nest in the bracts of the nipa palm tree, Nypa fruticans.

PH at habitats in Samut Sakhon province varied between 6.87-7.80 with salinity ranging from 1.1-10.6 ppt. Sympatric fish species include Trichopsis vittata, Trichopodus trichopterus, Anabas testudineus, Aplocheilus panchax, Oryzias javanicus, Dermogenys siamensis, Channa striata, and Boraras uropthalmoides.

Nonn Panitvong/Siamensis.org

B. mahachaiensis can be distinguished from congeners by the following combination of characters: base body colour brown to black with iridescent green to bluish-green pigmentation; presence of two parallel iridescent green to bluish-green vertical bars on opercle; brown-to-black opercular membrane without red streaks or patches; dorsal, caudal, and anal-fin rays brown to black contrasting with iridescent green or bluish-green interradial membranes; dorsal fin with transverse black bars in proximal two-thirds or more; absence of dark transverse bars on caudal-fin but presence of small black rounded marks flanking the internal rays on interradial membranes; pelvic fin brown to black with iridescent green/bluish-green anterior margin and white tip; head length 24.9–31.2% SL; postdorsal length 17.1–25.2% SL; length of dorsal fin base 12.2–19.3% SL; pelvic fin length 21.2–49.6%; pectoral fin length 15.4–21.3% SL; orbit diameter 22.8–29.7% SL.

The full description paper is open access and available via the following link: Kowasupat, C., B. Panijpan, P. Ruenwongsa, and N. Sriwattanarothai. 2012. Betta mahachaiensis, a new species of bubble-nesting fighting fish (Teleostei: Osphronemidae) from Samut Sakhon Province, Thailand. Zootaxa 3522: 49-60