Diplodus annularis is a fish belonging to the sea breams family (Sparidae) that inhabits the seagrass meadows of Zostera algae, as well as coastal rocky bottoms up to depths of 90 meters, although above 20 meters is where it is more frequent. This species is distributed in the waters of the Atlantic Ocean from the Bay of Biscay to the coasts of Madeira and the Canary Islands. It is also present throughout the Mediterranean Sea.
The body of Diplodus annularis is oval in shape, being quite compressed laterally. It reaches sizes of 20-25 cm maximum, although usually we will observe specimens of about 15 cm in total length. It has a slightly extensible terminal mouth with 8 incisor teeth in each jaw followed by 2-4 rows of molars in the upper jaw and 2-3 rows in the lower jaw. The dorsal fin of Diplodus annularis has 11 spines followed by 11-13 soft rays forming a single dorsal fin. The anal fin is formed by 3 spines and 11-12 soft rays. The color of the body is yellowish gray with silver highlights. It has no vertical bands on its body, nor a spot located on the nape of the neck, nor a spot located at the origin of the latera line, all these distinctive features of other species of the same family. On the caudal peduncle we can observe an annular black stripe, very intense in juveniles, which begins just after the end of the dorsal and anal fins. The pelvic fins are yellowish. On the flanks of juveniles we can observe 5 vertical stripes that can be more or less intense depending on the specimen.
The reproduction of Diplodus annularis occurs during the months of February and September, when the sexually mature specimens lay eggs that become part of the plankton. Sexual maturity in this species is reached when the specimens are approximately 10 cm in total length. In a first stage all specimens are males, and later they become females, that is to say they are protandric hermaphrodites.
In the Mediterranean there are other species of the genus Diplodus that could be confused. Their distinguishing features are:
- Diplodus annularis: black spot on the base of the tail, without transverse bands.
- Diplodus cervinus: 5-6 transverse bands that are very wide.
- Diplodus puntazzo: alternation of about 6 broad and marked transverse bands with narrow and faint ones.
- Diplodus sargus: 8 to 9 well-marked transverse bands.
- Diplodus vulgaris: 15-16 golden transverse lines; black spot on nape to pectoral fins; annular black spot on caudal peduncle.