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🌊 Marine Least Concern 🌡️ Tropical

Paperhead croaker

Johnius novaeguineae Nichols, 1950
Max Length
9 cm
Max Weight
-
Lifespan
-
Trophic Level
3.3
Depth
-
Climate
Tropical
Resilience
High
Vulnerability
11.00/100
Typical Length
7 cm
Depth Zone
-

📖 Overview

Paperhead croaker (Johnius novaeguineae) is a ray-finned fish of the family Sciaenidae. It inhabits marine (saltwater) waters. This species can reach a maximum total length of 9 cm. With a trophic level of 3.3, it is a low-level carnivore, feeding on invertebrates and small organisms. It is assessed as Least Concern on the IUCN Red List.

Scientific Name
Johnius novaeguineae
Authority
Nichols, 1950
Habitat
Marine
Climate
Tropical
Body Shape
Fusiform / normal
IUCN Status
LC
Max Length
9 cm
Trophic Level
3.3
Resilience
High
Vulnerability
11.00/100
Salinity
30–40 ppt

🐟 Physical Description

Dorsal spines (total): 8 - 10; Dorsal soft rays (total): 25 - 30; Anal spines: 2; Anal soft rays: 6 - 8. Head swollen and deep. Eye very small, 11 to 16 % of head length; snout very steeply rounded, but not swollen or projecting; mouth very large, strongly oblique; no barbel; no upper rostral pores; mental pores in one pair only, open behind symphysis; teeth well differentiated into large and small in both jaws; gill rakers long, slender, equal to or longer than gill filaments at angle, 16 to 18 on lower limb. Dorsal fin with VII to IX (most frequently VIII) spines. Second anal spine long, slender, 31 to 44 % of head length; caudal fin acutely pointed. Swim bladder hammer-shaped, with 11 pairs of arborescent appendages along its side, the first pair entering head beyond transverse septum and sending a palmate branch to the front of pectoral arch. Sagitta (large earstone) with tadpole-shaped impression, the head of which has its long axis lying obliquely to that of sagitta and the tail expanded and deepened as a hollow cone connected with the head by a narrow groove.: fusiform / normal.

🌀 Behaviour

Behavioural data for Paperhead croaker is currently being reviewed.

🦐 Diet

aquatic invertebrates
small fish
algae
detritus

🥚 Reproduction

🐣 Oviparous 📦 Batch Spawner
Spawning Season
spring-summer
Spawn Location
Pelagic
Fertilization
External

🌍 Habitat & Distribution

Marine; brackish; benthopelagic. Tropical Central Pacific: New Guinea and northern Australia.

🌿 Ecology

Zone Preferences
🌊 Marine 🌿 Brackish
Trophic Level
3.3±0.4

📐 Morphometrics

Length–Weight Relationship: W = 0.00891 × L3.07 (TL)
Max TL
9cm
Dorsal Spines
9
Dorsal Rays
28
Anal Spines
2
Anal Rays
7

🌡️ Water Parameters & Tolerance

Salinity Range
30–40ppt

🛡️ Conservation Assessment

IUCN Category
Least Concern
Assessment Date
2019

📊 Population Risk & Fisheries

Population Resilience
High
Minimum doubling time
Fishing Vulnerability
11.00/100
Low vulnerability
Trophic Level
3.3
Predator
Body Shape
Fusiform / normal
Climate Zone
Tropical
Described By
Nichols, 1950

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