Morphology Data of Petrocephalus tanensis
Identification keys
Main Ref. Kramer, B., R. Bills, P. Skelton and M. Wink, 2012
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance always different morphology between mature adults
Different colors
Remarks Males with kink in anal fin base which is absent in juveniles and females where the anal fin base is straight (Ref. 91771).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral fusiform / normal
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales cycloid scales

Diagnosis: Body depth 25.7-35.6% of standard length; predorsal length 57.4-64.5% of standard length; dorsal fin length 16.7-22.2% of standard length; anal fin length 21.4-25.7% of standard length; distance dorsal fin to end of caudal peduncle 42.7-47.2% of standard length; depth of caudal peduncle 29.1-43.9% of its length; 22-27 dorsal fin rays (Ref. 91771).

Description: Body oval shape, dorsally deep and rounded, ventrally rather flat; head broadly rounded with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed (Ref. 91771). Dorsal fin origin situated almost two-thirds of standard length from snout, obliquely orientated, anteriorly higher and posteriorly lower, distal margin crescentic with anterior two or three rays longer than posterior rays, 22-27 dorsal fin rays (Ref. 91771). Anal fin longer than dorsal fin, opposite dorsal fin with slightly more anterior origin, obliquely orientated, anteriorly lower and posteriorly higher, anterior 10 or so rays longer than posterior ones, especially in males where they also appear stronger, margin broadly rounded, rays posterior to first 10 with distal margin straight, 26-29 anal fin rays (Ref. 91771). Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fins; scales in lateral series 36-38; scales on caudal peduncle circumference, 12-14 (Ref. 91771). Caudal peduncle slender, subcylindrical entire length, usually 19.3-24.7% of standard length (Ref. 91771).

Colour: In life, grey-silver, underside lighter, paired fins light and transparent (Ref. 91771). In preservation light ochre (Ref. 91771).

Ease of Identification

Meristic characteristics of Petrocephalus tanensis

Lateral Lines Interrupted: No
Scales on lateral line 36 - 38
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle 12 - 14
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 22 - 27
Adipose fin absent

Caudal fin


Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 26 - 29

Paired fins

Pectoral Attributes  
Pelvics Attributes  
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Boden, Gert
Modified by Bailly, Nicolas
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