Crystal goby
Otolith description
Otoliths of gobiidae are all very similar in shape and are hard to determine to species level. The shape of the otolith in crystal goby is rounded. The sulcus is not well-developed, closed and runs diagonally. The cauda is indistinct; the ostium may just be visible. The surface of the inside, the outside and margins are smooth. There is a no rostrum or antirostrum visible The margins are rounded. The inside of the otolith is slightly concave and the outside convex. The otolith is thick. Crystal goby is the smallest of gobiidae and otoliths do not exceed 0.7 mm in length.
Otoliths of gobiidae are all very similar. Otoliths of black goby Gobius niger, common goby Pomatoschistus microps, painted goby P. pictus, sand goby P. minutus and Lozano’s goby P. lozanoi are square in stead of round. Otoliths of transparent goby Aphia minuta have a well-developed sulcus and the cauda is distinct.
When eroded the above described differences disappear and are therefore not useful for identifying otoliths to species level. Eroded gobiidae otoliths are round with the sulcus slightly visible.
There is some difference in the maximum size of the fish and therefore in the otoliths:
crystal goby: <0.7 mm
transparent goby: <1.5 mm
common goby, Lozano’s goby: <2.0 mm
painted goby: <2.5 mm
sand goby: <3.0 mm
black goby: >3.0 mm
Fish length and distribution
Crystal goby is the smallest of gobiidae and can grow up to 5 cm. Crystal goby is a schooling fish (CRYSLINE.TIF) found mostly in offshore waters, in depths up to 400 m. It is mostly found in small schools near the surface. Spawning takes place from May to August and eggs are deposited on the seabed (Wheeler, 1978, Muus et al., 1999).
Crystal goby is found in the NE Atlantic and North Sea.
Sample origin
Southern North Sea.