Tag: White-Streaked Grouper (Epinephelus ongus)

The White-Streaked Grouper (Epinephelus ongus) is a fairly common member of of the Grouper (Serranidae) family which spends much of its time resting beneath corals, rocks or crevices.

Unlike many of its relatives, it is a particularly shy species, often dashing for cover when approached. This makes it relatively difficult to photograph and identify, and is probably the reason that it appears less common than it actually is.

Growing to a maximum size of around 40cm, the White-Streaked Grouper undergoes a dramatic change between its juvenile and adult stages. This is in contrast with many of its local relatives, such as the Black-Tip Grouper (Epinephelus fasciatus), which changes very little in physical appearance throughout its lifetime.

Adult White-Streaked Groupers are reasonably easy to identify with their overall olive green/brown - pale grey colouration with numerous small pale/white spots over the body and fins, many of which merge to form the white streaks from which it gets its "common" name.

The spot/line markings may be noticeably less distinctive, or almost completely absent from the head, particularly around the face and gill cover (operculum) areas.

The dorsal, anal and rounded caudal fins have a dark, diffuse sub-margin edged with a narrow white margin which is lacking from the ventral and pectoral fins.

The pectoral fins may also exhibit fewer spot markings than the rest of the body whilst the ventral fin may be totally lacking in markings.

In stark contrast to the adults, the juvenile (which is rarely seen) is a very distinctive black overall with white "polka dots" covering its entire body and fins, including the translucent yellow pectoral fins.

As with many local fish species, it seems the juvenile White-Streaked Grouper seeks the protection of the shallower reef areas such as those at the Angthong Marine Park, before venturing out to the deeper offshore locations such as Sail Rock where it is frequently encountered.

The White-Streaked Grouper (Epinephelus ongus) is a fairly common member of of the Grouper (Serranidae) family which spends much of its time resting beneath corals, rocks or crevices.

Unlike many of its relatives, it is a particularly shy species, often dashing for cover when approached. This makes it relatively difficult to photograph and identify, and is probably the reason that it appears less common than it actually is.

Growing to a maximum size of around 40cm, the White-Streaked Grouper undergoes a dramatic change between its juvenile and adult stages. This is in contrast with many of its local relatives, such as the Black-Tip Grouper (Epinephelus fasciatus), which changes very little in physical appearance throughout its lifetime.

Adult White-Streaked Groupers are reasonably easy to identify with their overall olive green/brown - pale grey colouration with numerous small pale/white spots over the body and fins, many of which merge to form the white streaks from which it gets its "common" name.

The spot/line markings may be noticeably less distinctive, or almost completely absent from the head, particularly around the face and gill cover (operculum) areas.

The dorsal, anal and rounded caudal fins have a dark, diffuse sub-margin edged with a narrow white margin which is lacking from the ventral and pectoral fins.

The pectoral fins may also exhibit fewer spot markings than the rest of the body whilst the ventral fin may be totally lacking in markings.

In stark contrast to the adults, the juvenile (which is rarely seen) is a very distinctive black overall with white "polka dots" covering its entire body and fins, including the translucent yellow pectoral fins.

As with many local fish species, it seems the juvenile White-Streaked Grouper seeks the protection of the shallower reef areas such as those at the Angthong Marine Park, before venturing out to the deeper offshore locations such as Sail Rock where it is frequently encountered.

Alan's picture
White-Streaked Grouper (Epinephelus Ongus)

This photograph of an adult White-Streaked Grouper (Epinephelus Ongus) at Sail Rock clearly shows the main distinguishing features of the species in local waters eg.

Alan's picture
White-Streaked Grouper (Epinephelus Ongus)

This photograph shows a paler-coloured adult White-Streaked Grouper (Epinephelus Ongus) at Mae Haad/Koh Ma.

Alan's picture
White-Streaked Grouper (Epinephelus Ongus)

An adult White-Streaked Grouper (Epinephelus Ongus) shares a crevice with a Redcoat Squirrelfish (Sargocentron Rubrum) at Sail Rock.