Gobies and how to identify them
There are lots of gobies which can be found in rock pools and shallow sea but they can look very similar at a glance so making a positive identification can be quite difficult. Even the type of environment can be used to help differentiate some species from other very similar species, large black gobies (Gobius niger) for example can look very similar to sub adult giant gobies (Gobius cobitis). Most gobies are extremely variable in colour too which further complicates things.
Gobies can be recognised from their quite similar relatives the blennies quite easily by looking closely at some of their characteristics.
Gobies have two separate dorsal fins where blennies have a single dorsal fins which runs along most of their backs. Gobies have a fused pelvic fin where blennies have two separate pelvic fins and in most cases blennies have cirri which are ornate growths above each eye,
On the left is a goby and on the right a blenny.
Fin rays key:
Numbers are used for soft rays and Roman numerals are used for stiff rays
The first two fish pictured above are of the very same fish and taken just two day apart. This first photo was taken immediately after capture and the second photo after the fish had been in our aquarium for 48 hours it shows just how variable gobies can be in different environments. The third photo is of a wild two spot goby in a rock pool.
Fin rays: D1: VII (VII - VIII); D2: I + 9 - 10; A: I + 9 - 10; P: 17 - 18;
Length: 6 cms.
Colour features: Large black spot below the first dorsal and another at the base of the tail.
Habitat: Shallow water among rocks and weed, unusually for a goby they spend most of their time swimming in mid water.
Two spot gobies are common along the south and west coast line but less common along the east coast of the UK. They breed from spring to late summer. It is unlikely that these gobies could be mistaken for another.
Fin rays: D1: VI (V - VII); D2: I + 9 (7 - 10); A: I + 8 - 9; P: 18 - 19 (16 - 20);
Length: 5.7 cms.
Colour features: One or two rows of spots on the first dorsal.
Habitat: Inshore and down to 50m, over sand or gravel.
Painted gobies are found all around the UK but seem to be most common along the south coast. They are extremely well camouflaged in their natural habitat as can be seen in the photos. Painted gobies are a bottom living species and rarely swim mid water.
Fin rays: Dl: VI; D2: I + 13 - 14 (12 - 15); A: I + 11 - 12 (10 - 13); P: 21 - 22 (18 - 23);
Length: 12 cms.
Colour features: The colour is extremely variable but there is a band of cream to red along the top edge of the first dorsal.
Habitat: Inter tidal under stones, and in weedy rock pools.
Rock gobies are most common on the south coast but can be found all around the UK where there is suitable habitat. Rock gobies are relatively large gobies but they are easy to identify using the band of colour along the top edge of the first dorsal. Occasionally this band of colour is quite pale and may go unnoticed the fish may then be confused with both Gobius niger and Gobius cobitis.
Fin rays: Dl: VI; D2: I + 13 (13 - 14); A: I + 11 (10 - 12); P: 20 - 21 (19 - 22);
Length: 27 cms.
Colour features: Breeding males are dark with white edges to unpaired fins.
Habitat: Sheltered rock pools with stones and weed cover. Giant gobies can be found high up the intertidal zone.
Giant gobies as their name suggests are large gobies and adults cannot be mistaken for any other goby. Juveniles are very similar to both rock gobies and black gobies.
They are only found very rarely and only on parts of the south coast. The south coast of the UK represents the most northerly part of their natural range. Giant gobies are a protected species and it is illegal to catch, harm or even disturb one with a maximum penalty of six months in prison.
Fin rays: Dl: VI (V - VII); D2: I + 89 (8 - 11); A I: + 8 - 9 (7 - 10); P: 17 - 19 (15 - 20);
Length: 6.4 cms.
Colour features: Males have up to 10 vertical bars on their flanks, males also have a dark spot to the rear of D1.
Habitat: Inshore, found in pools right up to the high tide mark, and locked lagoons, salt marshes, and estuaries. They are found out in the open over sand or mud and in rocky weedy areas too.
Common gobies can easily be mistaken for sand gobies. Sand gobies tend to be less transparent and have a more solid colour. They are common all around the UK.
Fin rays: Dl: VI (VI - VII); D2: I + 10 - 12; A I + 9 - 12; P 18 - 2;
Length: 9.5 cms.
Colour features: Four vertical bars present on both sexes and dark wedge shaped spot to the rear of D1 present on both sexes.
Habitat: In shore over sand and mud.
Sand gobies are common all around the UK