Morphology Data of Nannothrissa stewarti
Identification keys
Main Ref. Whitehead, P.J.P., 1985
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs no special organs
Different appearance males alike females
Different colors males alike females

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral fusiform / normal
Cross section compressed
Dorsal head profile more or less straight
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales cycloid scales

Diagnosis: Body slender or moderate, depth about 25% of standard length; scutes a little behind isthmus, very strongly keeled, 9-10 pre-pelvic and 7-9 post-pelvic scutes; lower jaw very slightly projecting, toothless; no teeth on premaxillae or maxillae; posterior supra-maxilla as deep as maxilla blade and with long slender anterior shaft; lower gillrakers 20-23; pelvic fin with 1 unbranched and 6-7 branched rays, its insertion just below dorsal fin origin; anal fin rays 17-19; scales in lateral series 34-35 (Ref. 188, 94752). It differs from Nannothrissa parva in having fewer gillrakers, 20-23 vs. 24-31, fewer anal fin rays, 17-19 vs. 20-23, and fewer scales in lateral series, 34-35 vs. 35-40 (Ref. 188, 94752).

Description: Body depth about 25% of standard length; caudal peduncle 1 to 1.18 times as long as deep (Ref. 188, 94752). Number of lower gillrakers 20-23 (Ref. 188, 28136, 94752). Dorsal fin with 14-16 rays; anal fin with 17-19 rays; pectoral fin with 13 rays; pelvic fin with 1 unbranched and 6-7 branched rays, its insertion just below dorsal fin origin (Ref. 188, 94752). Scales in longitudinal series 34-35 (Ref. 188, 28136, 94752). Ventral scutes well developed; 9-10 pre-pelvic scutes, with 1 pre-pectoral scute without ascending arms and 9 pre-pelvic scutes with ascending arms, and 7-8 post-pelvic scutes with ascending arms, sometimes followed by 1 scute without ascending arms (Ref. 188, 94752). Number of vertebrae 38-39 (Ref. 94752).

Colouration: Silvery coloured, with a faint black spot at the base of the caudal fin, a series of small black dots at the origin of the anal rays, a blackish occiput and some small spots on the opercular region (Ref. 94752). Living specimens are characterized by a pronounced bluish reflection of the whole body (Ref. 94752).

Ease of Identification

Meristic characteristics of Nannothrissa stewarti

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series 34 - 35
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Gill clefts (sharks/rays only)
Gill rakers
on lower limb 20 - 23
on upper limb
total 38 - 39


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 14 - 16
Adipose fin absent

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 17 - 19

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   13 - 13
Pelvics Attributes  more or less normal
Position    abdominal  beneath origin of D1
Spines     0
Soft-rays   7 - 8
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Binohlan, Crispina B.
Modified by Boden, Gert
Comments & Corrections
Sign our Guest Book
Back to Search
cfm script by eagbayani, 17.10.00, php script by rolavides, 13/03/08 ,  last modified by sortiz, 06.27.17