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Freshwater Collective

Common diadromous species of Hong Kong

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Very flat carapace and legs. Dark brown to brown in colour, except for chelae, which can have shades of dark red with tips that are white. All legs have hair.

Varunidae

Varuna yui

Swimming crab

游氏弓蟹

WWF HK status

Large, thick, compact carapace that is dark brown-green in colour with long slender legs built for climbing. Juveniles tend to have a mottled light brown colouration throughout. Chelae are big and have hair, but this is absent in juveniles. There are some hairs on the legs as well but not as dense as Varuna yui.

Varunidae

Eriocheir japonica

Japanese mitten crab

日本絨螫蟹

WWF HK status

Elongated body with scales embedded under skin resulting in a smooth and ‘slippery’ surface. Dorsal and anal fins conform as a single fin flowing along the belly, tail, and back. Dorsal side tends to be grey-brown in colour with a pale white belly.

Anguillidae

Anguilla japonica

Japanese eel

日本鰻鱺

WWF HK status

Elongated and thick body with scales embedded under skin resulting in a smooth and ‘slippery’ surface. Dorsal and anal fins conform as a single fin flowing along the belly, tail, and back. Dorsal side dark brown – olive in colour with dark mottled patterns and a pale white – yellow belly.

Anguillidae

Anguilla marmorata

Giant mottled eel

花鰻鱺

WWF HK status

Elongated body with a dorsally compressed head and large mouth. Yellow-brown coloration across the head and body. Black blotch at pectoral fin base surrounded by two orange blotches. Orange margins at the lower margins of pelvic, anal, and caudal fins. Previously misidentified as Butis melanostigma.

Eleotridae

Butis humeralis

Olive-flathead gudgeon

黑點嵴塘鱧

WWF HK status

Stout cylindrical body with light brown dorsal side (sometimes banded) and dark lateral sides. Capable of changing body colour and patterns for camouflage. Sharper and less blunt head than Eleotris acanthopomus with a large mouth.

Eleotridae

Eleotris oxycephala

Sharphead sleeper

尖頭塘鱧

WWF HK status

Slender body with small head and inferior mouth. This species exhibits sexual dimorphism. Males are metallic blue in colour, have black anal and caudal fins with a blue edge, and black dorsal fins with a red and blue edge. Females are yellow-grey in colour, with two lateral black stripes that go from their snout all the way to the caudal peduncle, which ends as two black blotches.

Gobiidae

Stiphodon atropurpureus

Blue neon goby

紫身枝牙鰕虎魚

WWF HK status

Elongated body with a rounded head and a large oblique mouth. Yellow-brown coloration across the head and body with black blotches and red-blue spots along lateral sides. Red bars from the operculum to lower jaw. Red, yellow, and blue patterning on the dorsal, anal, and caudal fins.

Gobiidae

Rhinogobius similis

Amur goby

子陵吻鰕虎魚

WWF HK status

Slender body with small head and inferior mouth. This species exhibits sexual dimorphism. Males are brown-grey in colour, have yellow-red dorsal, anal and caudal fins, and a series of transverse bars along the lateral body. Females can be differentiated from other Stiphodon species based on two to four black spots on the second dorsal-fin spine and soft rays, reddish marks the on tip of the first and second dorsal fins.

Gobiidae

Stiphodon multisquamus

Goby

多鱗枝牙鰕虎魚

WWF HK status

Transparent body with a rounded head and large mouth. Bones, organs, swim bladder, and eggs clearly visible. Looks similar to larvae of Rhinogobius similis at a glance but can be differentiated by having a superior mouth (vs oblique).

Gobiidae

Gobiopterus macrolepis

Large-snout goby

大鱗鰭鰕虎魚

WWF HK status

Flat elongated body with a rounded head and a large oblique mouth. Body in varying shades of brown with 5-6 rounded blotches on the lateral side of the body. This species can change colour rapidly to match its surroundings.

Gobiidae

Glossogobius giuris

Tank goby

舌鰕虎魚

WWF HK status

Streamlined and compressed body with a forked caudal fin. Lower jaw projects beyond the snout with a large eye that reflects a red-pink colour when shined with light.

Megalopidae

Megalops cyprinoides

Indo-Pacific tarpon

大眼海鰱

WWF HK status

Slender and streamlined body with a grey coloured dorsal side that turns silvery-white from the lateral to ventral body. Mullet are notoriously difficult to identify but the grey mullet can be differentiated from other species by the blue blotch on the pectoral fin base in Hong Kong.

Mugilidae

Mugil cephalus

Grey mullet

烏頭

WWF HK status

Semi-translucent body with a wide variety of possible colours, from red, blue, yellow, green, and brown. Occasionally, a latitudinal stripe can be found on the dorsal side of the carapace to end of the tail. Can be differentiated from non-migratory shrimps by the long rostrum and numerous small eggs in females.

Atyidae

Caridina elongapoda

Dwarf shrimp

米蝦

WWF HK status

Usually with a semi-translucent body with a single vertical bar approx. the 2-3 segment of the dorsal side of the abdomen. Mature males can be dark brown to almost black in colour throughout. Chelae usually brown to dark green but can vary. In semi-translucent individuals, there will be three irregular vertical stripes on both sides of the lateral side of the carapace.

Palaemonidae

Macrobrachium formosense

Taiwan river prawn

台灣沼蝦

WWF HK status

Semi-translucent body with a single vertical bar approx. the 2-3 segment of the dorsal side of the abdomen. The defining feature is the leopard print-like chelae, in large males the tips will also be covered with short dense hairs.

Palaemonidae

Macrobrachium equidens

Rough river prawn

等齒沼蝦

WWF HK status

Dark brown to greenish in colour with square-triangular markings throughout the shell. Most individuals will have some degree of spire erosion, with more prominent erosion in larger individuals

Neritidae

Clithon retropictum

Nerite snail

石蜑螺

WWF HK status

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