One of the earliest described and most studied sicydiins. Watched many individuals (sizes circa 2-8cm) in lower reach of clear fast flowing stream with large boulders and rocky bottom. Water should be fresh and low salt content although its reaching the beach and mangrove soon. Isolated stepwise rock pools and rapids. Male in breeding color typically with red caudal and white pectoral fins, white dot in front of snout really looks like "rabbit's head". saddle shaped dark patches along the back. Female drape color with large belly and horizontal dark bar along the body sides.

Not easy to watch close and keeping about 1 metre distance from me. Noted a male guarding a territory over big boulder, about 4-6m in range diametric. Bottom with smaller individuals and other goby species probably Favonogobius and/or Rhinogobius. Kuhlia and probably Lutjanus in midwater. Water plant scarce.

S. largocephalus mostly attached to rock and in gracing motion scraping attached algae/diatom/substrate from rock surface. Swimming motion by quick darting or longer distance straight motion. May hide in holes and substrates, dominant male in display around territory and chasing individuals especially males out.

[ 本帖最後由 jasonpoon 於 2017-8-18 10:51 編輯 ]

The third pic probably a younger male not in breeding or dominant color, the fourth pic should have mistaken as a female but looked more like a male also in color.

Field ID for dominant male unmistakable, that of smaller individuals and females may confuse with other sicydiins if present.

It is suggested by a japanese fishwatcher that smaller co-habiting gobies could be Rhinogobius sp. possible R. nagoyae.