📖 Overview
Inhabits algal and seagrass flats and shallow lagoon and coastal reefs . Forms schools. Mainly diurnal. Juveniles feed on filamentous algae, adults feed on leafy algae and seagrasses . Commercially cultured in Japan. Commonly found in large estuaries . Anterolateral glandular groove with venom gland .
Scientific Name
Siganus fuscescens
Body Shape
Short and / or deep
🐟 Physical Description
Dorsal spines (total): 13; Dorsal soft rays (total): 10; Anal spines: 7; Anal soft rays: 9; Vertebrae: 13. Body olive green or brown above, silvery below; fish frequently with a dark patch below origin of lateral line. Adults become mottled when frightened. Slender, pungent, venomous spines. Preopercular angle 89°-95°. Lower half to 2/3 of cheeks commonly covered with weak, scattered scales. Midline of thorax between pelvic ridges. Differs from S. argenteus in details of coloration and less deeply forked tail .: short and / or deep; Cross section: compressed.
🌀 Behaviour
Behavioural data for Mottled spinefoot is currently being
reviewed.
🦐 Diet
algae
aquatic plants
detritus
🥚 Reproduction
Size at Maturity
12.9cm TL
In Belau, ripe individuals form prespawning congregations of 30-60 individuals in shoal areas of inner reef flats; spawning occurs on the 4th or 5th day of the new moon; spawning sites are near reef edge. About 300,000 eggs/female at a single spawning. Individuals that spawn in consecutive yrs. & that 2+ yr. class fish could spawn more than once in a single season. Aug (Ref 1754) in Belau.
🌍 Habitat & Distribution
Marine; brackish; reef-associated; oceanodromous ; depth range 1 - 50 m . Tropical; 42°N - 37°S, 90°E - 171°E
🌿 Ecology
Zone Preferences
🌊 Marine
🌿 Brackish
🪸 Reef Associated
🐠 Schooling
Food Items
filamentous algae, adults feed on leafy algae and seagrasses (Ref
📐 Morphometrics
Length–Weight Relationship:
W = 0.01288 × L3.04
(TL)
🌡️ Water Parameters & Tolerance
🛡️ Conservation Assessment
IUCN Category
Least Concern
📊 Population Risk & Fisheries
Population Resilience
High
Minimum doubling time
Fishing Vulnerability
21.00/100
Low vulnerability
Trophic Level
2
Omnivore / Planktivore
Body Shape
Short and / or deep
Latitude Range
42°N
–
37°S
Described By
Houttuyn, 1782
⚠️ Venom Profile
Medical Warning: This species is venomous. Seek immediate medical attention
if envenomated.
Contact emergency services and follow first aid guidance below.
Venom Type
proteinaceous neurotoxin
Delivery
dorsal, anal, and pelvic fin spines
Antivenom
✗ Not Available
Named Toxins
high-molecular-weight protein (Stonustoxin analogue)
acetylcholine
Symptoms
- immediate intense pain
- swelling
- erythema
- occasional nausea and weakness
Affected Body Systems
peripheral nervous system
cardiovascular
First Aid
Immerse affected area in hot water (45 C, tolerable) for 30-90 minutes to denature toxin. Do not apply ice.
Medical Treatment
Analgesia; wound care; tetanus prophylaxis; severe cases may require monitoring for systemic effects.
References:
Compiled from Bhide (2018), Halstead et al. (1988) and family-specific envenomation literature
🎣 Angling Guide
Fight Rating
strong pulls with head-shakes
Best Seasons
spring,summer,fall
Best Time
incoming tide, dawn and dusk
Rod Type
medium-heavy spinning
Catch & Release
✓ Recommended
Best Months
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Techniques
bottom fishing
popping cork
soft plastics
live bait
Bait & Lures
live shrimp
cut mullet
soft plastic paddle-tails
popping corks
Recommended Tackle
-
medium-heavy 7ft spinning rod
-
30-50 lb braid
-
fluorocarbon leader
Where to Find Them
-
grass flats
-
oyster bars
-
marsh drains
-
deeper channel edges
Tips & Tricks
Popping cork technique attracts fish from distance. Fish moving tides.
Catch & Release Tips
Use barbless hooks, minimise air exposure, and revive fish head-first in current before release.
Regulations Summary
⚠️
Slot limits protect breeding-size fish. Verify daily bag limits.
🍽️ Edibility & Flavour
"Mottled spinefoot is an edible species."
✗ Not for Raw
✓ Fresh Indicators
- Clear, bright eyes — cloudy eyes indicate age
- Firm flesh that springs back when pressed
- Fresh ocean smell, never strong or ammonia-like
- Bright red or pink gills, not grey or brown
- Shiny, moist skin with scales tightly attached
✗ Avoid If
- Cloudy or sunken eyes
- Strong fishy or ammonia odour
- Soft, mushy flesh that doesn't spring back
- Discoloured or dry flesh
Best Cooking Methods
Baking
Grilling
Pan-frying
⚡ Nutrition
Per 100g cooked - Source: USDA FoodData Central
| Nutrient |
Amount |
| Protein |
19.2 g |
| Omega-3 (total) |
145 mg
|
🔬 Mercury Safety
Mercury data for Mottled spinefoot has not yet been
assigned. Please consult FDA/EPA guidance for general seafood safety advice.
🌿 Sustainability
Best Choice
Healthy stocks, low impact
Good Alternative
Well-managed, minor concerns
Use Caution
Check sourcing and season
Avoid
Overfished or high impact
✓ Sustainable Choice
🔬 Full Nutritional Profile
Per 100g - Raw, per 100g
- Source: USDA FoodData Central templates (generic fish average)
Proximate Composition
Energy125 kcal
Moisture75 %
Protein20 %
Total Fat4 %
Ash1.3 %
Fatty Acids (g)
Saturated Fat1 g
Monounsaturated Fat1.2 g
Polyunsaturated Fat1.5 g
Omega-3 Total1 g
EPA0.3 g
DHA0.5 g
Omega-6 Total0.3 g
Key Minerals & Vitamins
Calcium20 mg
Iron0.7 mg
Magnesium30 mg
Phosphorus220 mg
Potassium380 mg
Sodium55 mg
Zinc0.5 mg
Selenium32 µg
Vitamin B122 µg
📊 Population Dynamics
| Year |
Region |
Index |
Notes |
| - |
- |
- |
|