Author: Fraser & Prokofiev, 2016
Comments: This species has been taken in shrimp trawls on muddy bottom. Most specimens were collected from 70-119 m, some from 40-60 m, in the main waterway of the Bay of Nha Trang (latter samples might have been pumped through canyons cutting out the outer shelf as proposed for
  other fish taxa collected from the unusually shallow depths in this area (Ref. 84063). No specimens or fragments of sea urchins commonly trawled together with <i>Siphamia</i> specimens. Year-to-year fluctuations in density of population were observed with this species present at 18 of 22 stations trawling eastward and southward of Pyramid Island in 2005 and 2007 and two of 17 stations sampled in 2006 and 2009-2012. All samples were made between April and July, and no specimens were collected during a winter monsoon season (October-January). It always appeared in groups of about 10-60 specimens per trawl, with many specimens having ripe ova or brooding eggs. The smallest, 1.45 cm SL was immature. The males with buccal enlargement suggestive of brooding eggs were 2.2-2.4 cm SL and showed loss of teeth on the vomer and palatines. A 2.3 cm SL male had approximately 280 orangish eggs, 0.5 mm in diameter. Females with developed ova were as small as 2.3 cm SL. The largest gravid female was 2.95 cm SL. No possible indications for commensal relationships of this species were present (Ref. 110227).