The 'true gobies' represent more than 2,000 species and are one of the largest families of fish, representing almost 10% of all known fish species, with 10 - 20 new species discovered each year.
Most gobies are small, with the vast majority less than 10cm, and some as small as 9 mm. A few larger species can reach over 30 cm in length, however this is unusual.
They have two separate dorsal fins, and as the pelvic fins develop, they fuse together to create a disc-shaped sucker which can be used to stick to rocks or corals.
Gobies are a bottom-dwelling fish, with some species of marine gobies building elaborate burrows, some living only in caves, others living inside sponges or on corals.
Both male and females often live in pairs, and like many other fish species, some members can change sex during their lives. What is unusual about some gobies is that they can change sex from female to male, and then back to female again. Other fishes can only undergo a single sex change.
The Banded Goby has several colour variations, ranging from a pale grey to dark brown body.
There are dark stripes on the head and forebody, and several darker bars toward the rear body. These stripes and bars may not be very clear on darker variations.
All variations have a black spot on the first dorsal fin. Most variations have a dusky spot on the upper tail, near the tail base, and a dark spot above the pectoral fin, close to the gill cover.
The Banded Goby grows to 13 cm, but usually observed around 10 cm or smaller, and can be found over sandy or rubble areas at the reef edge. This species feeds by gulping mouthfuls of sand from the seafloor and sifting out algae and invertebrates.
The Blueband Goby, or Bluestreak Goby has a white or grey body with a yellow face and snout. There is a bright blue stripe under the eye to the pectoral fin and several blue spots and markings on the head, gills and chin.
The Blueband Goby grows to 15 cm, but usually observed around 10 cm. This species is usually found in pairs over sand and rubble areas at the reef edge feeding by sifting mouthfuls of sand. The diet includes small invertebrates, fish, and fish eggs.
The Steinitz' Shrimpgoby has a white body with five vertical brown bars on the head and body. There are tiny yellow spots on both dorsal fins and on the upper body. There may be a very faint sixth bar, or blotch on the tail base. The iris is dark, or black.
Some variations of Steinitz' Shrimpgoby are very similar, but with much narrower body bars and a darker iris.
The Steinitz' Shrimpgoby grows to 8 cm and shares a burrow with one or more snapping shrimps of the genus Alpheus. These nearly-blind shrimp work tirelessly all day to excavate long burrows of up to one metre, and when above ground they always keep one antenna touching the goby tail to receive warnings of approaching danger.
The burrows run close to the surface and need to be continuously re-excavated due to collapse.
The Barred Shrimpgoby is variably coloured, and may have a pale body with four irregular brown bars, or a dark brown body with several whitish saddles on top of the head and along the back. Both variations have white or bluish streaks and spots on the head, forebody, pectoral and anal fins. The dorsal fin is unmarked.
The Barred Shrimpgoby grows to 8 cm and, similar to Steinitz' Shrimpgoby, shares a burrow with one or more snapping shrimps of the genus Alpheus.
The excavating shrimp create extensive burrows, with tunnels around 3 cm in diameter which connect 2 or 3 larger chambers within the network. Occasionally the goby will dart away from the burrow entrance to take a mouthful of sand which is sifted for food.
The Twotone Dartfish has a pale blue to greyish head and forebody, fading quickly to a very dark blue colouring on the rear body and second dorsal fin.
The tail is pale, forked and has dark margins. The gill covers may have small bright blue markings.
The Twotone Dartfish grows to 13 cm, but usually observed around 8 cm - 10 cm. This species lives in sandy burrows close to the reef edge and is almost always seen in pairs.
The Spottail Dartfish has a long, thin, pale blue, or bluish grey body. The tail fin is yellow, with a large dark streak or spot in the middle.
The Spottail Dartfish lives over sand and rubble patches or hard substrates around the edges of a coral reef.
Adults are usually seen in pairs and share a burrow which is often under a rock or a piece of coral rubble. Occasionally several pairs are seen together.
Spottail Dartfish feed in pairs on zooplankton up to several meters above their burrow.
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Allen, G., Steene, R., Humann, P., DeLoach, N. (2003) Reef Fish Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications, Inc., ISBN 1-878348-36-1.
