Bony fishes

GobiesGobiidae

Family54 species

No family of marine fish has more species in it. More than two thousand gobies have been described, and the number moves every year, which is what happens to a group of animals that are small, sedentary and easily cut off from each other: a population on one patch of rubble does not mix much with the population on the next one, and given enough time it stops being the same fish.

The equipment that made that possible is under the chin. In a goby the two pelvic fins are fused into a shallow cup, and the cup works as a suction disc. Most of the family has also given up the swim bladder, so a goby does not hover; it holds on. That one change turns surfaces into addresses. A coral branch, the stem of a sea whip, the inside of a sponge, the roof of a cave, wave-hammered rock in the first meter of water: a goby can be stuck to any of them, in current that would roll an ordinary fish off the bottom.

Being small is the other half of it. A goby fits into spaces that are not habitat for anything else - a burrow dug and maintained by a snapping shrimp, the gap between the branches of one coral head it will never leave - and that is a whole living nobody else can take. The price is a short life at the bottom of the food chain, and the family answers by maturing early and breeding often.

Fifty-four species are listed here, and a diver notices perhaps three of them. The one everybody meets is a shrimpgoby posted at its burrow mouth on open sand, propped on its fins, dropping out of sight as you close the last meter. The rest are on the underside of things.

How to recognise gobies

Bottom-dwellingStocky, big-headed, sits on the reef or sand rather than swims - scorpionfishes, groupers, gobies.

small size, typically under 10 cm
often resting motionless on the substrate
two separate dorsal fins
elongate body
pelvic fins often fused into a ventral disc

54 species in Gobies

Amblyeleotris

Shrimpgobies, and the slim pale end of them: whitish bodies crossed by five to seven red-brown bars, eyes set high, sitting at the mouth of a burrow that a blind shrimp digs and they watch over. Slimmer and paler than the Cryptocentrus on the next patch of sand.

Diagonal Shrimpgoby

Amblyeleotris diagonalis

Gorgeous Shrimpgoby

Amblyeleotris wheeleri

Magnus' Shrimpgoby

Amblyeleotris sungami

Steinitz Shrimpgoby

Amblyeleotris steinitzi

Triplespot Shrimpgoby

Amblyeleotris triguttata

Amblygobius

Sand-sifters, almost always in pairs. The fish takes a mouthful of sand, sorts out what is edible inside the mouth and blows the cleaned grains out through the gill covers, working a patch over methodically.

Butterfly Goby

Amblygobius albimaculatus

Nocturn Goby

Amblygobius nocturnus

Snoutspot Goby

Amblygobius esakiae

Bathygobius

Frillgobies of rocky shore and tide pools, where the water is warm, shallow and half the time barely there. The upper pectoral rays end in free filaments, which is the character the group is named for.

Dusky Frillgoby

Bathygobius fuscus

Spotted Frillgoby

Bathygobius cyclopterus

Bryaninops

Gobies that live on other animals - a whip coral, a gorgonian, a black coral bush, a sponge - clamped to the host by a sucker formed from the fused pelvic fins. Most are close to transparent, so what you actually see against the host is the eyes, the gut and a line of marks along the spine.

Bryaninops spongicolus

Whip Coral Goby

Bryaninops yongei

Cryptocentrus

The heavy shrimpgobies. Stockier and blunter than Amblyeleotris, darker, and covered in blue or green spots over the head that carry back onto the body. Same partnership with a shrimp, same burrow at the same kind of sand, a different-looking fish at the door.

Luther's Shrimpgoby

Cryptocentrus lutheri

Ninebar Shrimpgoby

Cryptocentrus cryptocentrus

LCEndemic

Red Sea Shrimpgoby

Cryptocentrus caeruleopunctatus

Steinhard’s Shrimpgoby

Cryptocentrus steinhardti

Y-bar shrimp goby

Cryptocentrus fasciatus

Ctenogobiops

The small shrimpgobies of clean open sand: under eight centimeters, pale, finely speckled, and quick to drop into the burrow. Easy to miss entirely, because at that size the fish reads as a mark on the bottom.

Sandy Shrimpgoby

Ctenogobiops feroculus

Scarlet Shrimpgoby

Ctenogobiops crocineus

Silverspot Shrimpgoby

Ctenogobiops maculosus

Eviota

Dwarfgobies, and the genus holds the shortest-lived vertebrate known - under two months from hatching to death. The ones here run from one to three centimeters, translucent, propped on their pelvic fins, hopping between perches rather than swimming.

Pepperminteye Dwarfgoby

Fusigobius

Sandgobies: semi-translucent fish sitting out on open sand and rubble rather than in a burrow or a hole, holding still until something comes too close. Marks on the dorsal fin and the tail base do the identifying.

Orange-Spotted Sandgoby

Fusigobius longispinus

Gnatholepis

Told by the face: a dark bar runs straight down through the eye, and a small orange spot sits just above the base of the pectoral fin. Both marks hold on a fish that is otherwise pale and lightly speckled.

Eyebar Goby

Gnatholepis anjerensis

Red Sea Eyebar Goby

Gnatholepis caudimaculata

Gobiodon

Coral gobies: stubby, scaleless, and living permanently inside a branching coral head, usually in a pair. The skin gives off a bitter toxic mucus that makes them foul to swallow, which is what lets a three-centimeter fish sit in the open among the branches.

Gobius

The Atlantic and Mediterranean genus, on rock and under stones rather than on coral - stocky brown fish resting on fused pelvic fins in shallow, often surge-swept water.

Periophthalmus

The mudskippers, and they spend more time out of the water than in it. Eyes mounted on top of the head like a frog, pectoral fins used as legs, and a habit of climbing onto mangrove roots and rock above the waterline.

Common Mudskipper

Periophthalmus kalolo

Silverlined Mudskipper

Periophthalmus argentilineatus

Vanderhorstia

Shrimpgobies of silty sand rather than clean, marked with orange bars and rows of blue spots, and carrying a tall first dorsal fin they hold raised at the burrow mouth.