The researchers compared its anatomy with eight specimens of P. blochii from the Seychelles and reported that the Malaysian fish closely matched the established diagnostic profile of the species. The record also clarifies an earlier Malaysian report that had been based on a photograph; on re-examination, the authors identified the photographed fish as P. sagittarius rather than P. blochii . The genus Priacanthus contains 13 species, seven of which have been recorded in Southeast Asia.

Before this specimen-based report, confirmed regional records of P. blochii existed for the Andaman Sea off Thailand, the Philippines and Indonesia. Indonesian records include Sumatra, Java, Bali, North Sulawesi, Maumere on Flores, Ambon and West Papua. The species has been collected at depths of 15–30 m and is considered to prefer reef areas, although the Malaysian specimen was taken by bottom trawl.

An earlier publication included Malaysia in the reported distribution of P. blochii , but the new record is distinguished by an identifiable museum specimen whose anatomical characters were examined directly rather than a photograph alone. It therefore extends the documented occurrence of the species into Malaysian waters while clarifying the status of the earlier record. The investigators collected metric and meristic data following established procedures, taking linear measurements with calipers to the nearest 0.1 mm and abbreviating standard length as SL.

Counts of dorsal- and anal-fin rays treated the last two soft rays of each fin as a single ray. The comparative dataset combined the Perak individual with reference material from the Seychelles, allowing the Malaysian specimen’s absolute measurements, percentages of SL and head length, and anatomical counts to be compared with another series of identified fish. This was a single-specimen distributional record with a focused anatomical assessment, not a population survey or an estimate of abundance in the region.

The body of the Malaysian specimen was oval and laterally compressed. Its dorsal profile rose gently from the snout to the base of the fifth dorsal-fin spine, then gradually declined toward the caudal-fin base. The ventral outline descended from the lower-jaw tip to the pelvic-fin insertion, ran roughly parallel to the body axis and then rose from the anal-fin origin toward the tail.

The lateral line was complete: it began above the anterodorsal tip of the opercle, rose rapidly to just below the base of the third dorsal-fin spine, lowered toward the caudal peduncle and continued straight to the caudal-fin base. Very small, ctenoid, non-deciduous scales covered the body except the lips and posterior margin of the opercle. The posterior edge of the preopercle was serrated, and the long spine on its angle ended just short of the opercular margin.

The snout was short and smaller than the large, rounded eye. The anterior and posterior nostrils lay in front of the orbit and close to one another; the anterior nostril was oval with a short, broad flap behind it, while the posterior nostril was slit-like. Gill rakers were well developed, rod-shaped and covered with small, dense spines.

The mouth was large and terminal, with the posterior tip of the maxilla extending beyond the anterior margin of the eye. The mandible projected considerably beyond the maxilla and ended in a pointed lower-jaw tip slightly above the level of the eye’s center. The upper jaw had two rows of conical, backward-curving teeth.

Lower-jaw teeth were slightly larger, conical and backward-curving, arranged in two rows anteriorly and one row posteriorly. The dorsal fin began just above the uppermost point of the posterior tip of the opercle. The tenth spine was the longest, and the third soft ray was the longest ray.

The anal fin originated just below the base of the eighth dorsal spine, and the anus was positioned immediately anterior to the anal-fin origin. The posterior end of the dorsal-fin base was slightly anterior to that of the anal-fin base. The uppermost point of the pectoral-fin base lay slightly anterior to the posterior tip of the opercle and below the lower eye margin, while the fin’s rounded posterior margin reached below the base of the sixth dorsal spine.

Pelvic fins inserted below and slightly behind the posterior margin of the eye. Their second ray was longest, and the last ray was connected to the abdomen by membrane. The caudal fin was truncate overall, with a convex posterior margin.

Proportional measurements of the Perak specimen fell within the ranges reported for P. blochii from the Seychelles. Body depth at the base of the sixth dorsal spine was 37.7% of SL, compared with a reported range of 34.1–39.8% for the Seychelles material. Head length was 35.6% of SL, within the comparison range of 32.3–37.7%, and orbit diameter was 15.4%, within 14.0–16.5%.

The longest pectoral-fin ray measured 48.0% of head length, compared with a Seychelles range of 45.4–51.6%. The tenth dorsal-fin spine was 1.59 times the length of the second dorsal spine, matching the mean reported for the comparison specimens. The anal-fin base was 35.6% of SL, the dorsal-fin base 57.3%, and the caudal-peduncle depth 8.8%.

These measurements, together with the anatomical counts, supported the identification of the trawled fish as P. blochii . Fresh coloration provided additional diagnostic information. The body was uniformly reddish silver, and the dorsal surface of the head was red.

The spines and rays of the dorsal, anal and pelvic fins were slightly pale red, while the fin membranes were reddish black. The bases of the anal- and pelvic-fin membranes were yellowish, and the membrane connecting the last pelvic ray to the body was whitish. The pectoral fin was transparent with reddish rays.

The caudal fin was red with a blackish posterior margin, the pupil was black and the iris was pale red. Among the features used in identification, the specimen lacked a black blotch on the membranes of the first two spinous dorsal rays and had a single large black blotch at the base of the pelvic fin. In combination with relatively low, distally rounded dorsal and anal fins and the convex posterior margin of the caudal fin, the coloration was consistent with the species’ diagnostic description.

Meristic counts placed the Perak fish within the reported range for P. blochii . It had 10 dorsal-fin spines and 13 dorsal soft rays, compared with a comparison range of 13–14 soft rays. The anal fin had three spines and 14 soft rays, within a range of 13–15.

It possessed 18 pectoral-fin rays, one pelvic spine and five pelvic rays, and the first gill arch carried five rakers on the upper limb and 16 on the lower limb, for a total of 21. The specimen had 69 lateral-line scales, 76 scales in the lateral series and 48 vertical scale rows, including 10 above and 37 below the lateral line. The corresponding ranges for the Seychelles specimens were 68–74 lateral-line scales, 76–83 scales in the lateral series and 48–51 vertical rows.

The authors concluded that the Perak specimen matched the combination of 13 dorsal soft rays, 14 anal soft rays, 21 total gill rakers, 77 scales in the lateral series in the comparative material, relative fin proportions and pelvic-fin blotch described by Starnes in 1988. The Malaysian record also prompted a correction to the status of a 2010 report by Ambak and colleagues, which had identified P. blochii from Malaysia from a photograph. The pictured individual had a strongly elongated tenth dorsal spine, elongated dorsal- and anal-fin rays and a black anterior portion of the dorsal fin.

According to the diagnostic information used in the study, those features characterize P. sagittarius , not P. blochii . The authors further noted that a distribution map in Starnes’s 1999 treatment probably connected localities shown in the earlier 1988 publication, while neither work displayed a Malaysian specimen. The Perak individual therefore establishes a first verified Malaysian occurrence supported by direct anatomical examination, measurements and comparison with reference material.

The scientific significance of the Perak record lies in its evidentiary clarity and geographic resolution. Priacanthus blochii is widely distributed across the Indo–West Pacific, and the new observation places an authenticated member of that assemblage in Malaysian waters, where a previous claim had rested on a photograph now judged to depict another species. The study does not establish the species’ population size, abundance trend or habitat preference in Malaysian waters; it concerns one bottom-trawl specimen collected from the Strait of Malacca.

The Perak fish, with its distinctive fin and scale counts, proportional measurements and fresh reddish-silver coloration, is now the verified Malaysian representative of the paeony bulleye.

Subject of Research: First specimen-based Malaysian record of the paeony bulleye, Priacanthus blochii , from the Strait of Malacca.

Article Title: First record of Priacanthus blochii ( Actinopterygii : Eupercaria : Priacanthidae ) from Malaysia

Article References: Hashimoto, S., Koreeda, R., Izarenah, M. R., Seah, Y. G., & Motomura, H. (2024). First record of Priacanthus blochii (Actinopterygii: Eupercaria: Priacanthidae) from Malaysia. Acta Ichthyologica et Piscatoria, 54, 243-247. https://doi.org/10.3897/aiep.54.134405

Image Credits: AI Generated

DOI: 10.3897/aiep.54.134405

Keywords: Priacanthus blochii, paeony bulleye, Malaysia, Perak, Strait of Malacca, fish taxonomy, species distribution, ichthyology, museum specimen, bottom trawl, First, record