A team of biologists has discovered a new species of bubble-nesting fighting fish in Samut Sakhon Province, Thailand.

The new species, called Betta mahachaiensis, belongs to the Betta splendens group in the family Osphronemidae.

B. mahachaiensis has a body length of about 1.4 inches (3.5 cm) and differs from other members of the B. splendens group by an iridescent green/bluish-green appearance on the brown-to-black body background.

The team, led by Dr Chanon Kowasupat of the Mahidol University in Nakhon Pathom, Thailand, describes the species in a paper in the journal Zootaxa: “male with dark-brown to black head, with iridescent green to bluish-green scales. Opercles with two parallel iridescent green to bluish-green vertical bars, opercular membrane brown to black, eyes with iridescent green to bluish-green patches at bottom and posterior regions. Body dark brown to black with iridescent green to bluish-green scales arranged in regular rows, with a similar iridescent area on each scale.”

“Female less colorful: head and body yellowish to light-brown with iridescent green to bluish-green scales; opercles pale gold with two faint iridescent green to bluish-green bars; throat with chin-bar.”

The name mahachaiensis is derived from Thai name for a subdistrict of Samut Sakhon Province – Maha Chai, the site where first specimens of the species were collected.

According to the biologists, the fish inhabits sites with nipa palms and brackish water: “B. mahachaiensis lives in brackish waters, some quite heavily polluted; pH at catch sites 6.87 – 7.80, salinity 1.1–10.6 ppt. The species was found in nipa palm (Nypa fruticans) swamps, especially, in the water-holding phytotelma of the palm bract, which the pair use for bubble-nest building, courtship, and hatching of fry.”

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Bibliographic information: Chanon Kowasupat et al. 2012. Betta mahachaiensis, a new species of bubble-nesting fighting fish (Teleostei: Osphronemidae) from Samut Sakhon Province, Thailand. Zootaxa 3522: 49–60