FishFreshwaterExpert
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Reef Stonefish
Synanceia verrucosa
The Lethal Rock (16 inches / 40 cm). The most venomous fish on planet Earth. Its sting will kill a human if anti-venom is not administered immediately.
Water Temperature
24 - 27 °C
pH Value
8.1 - 8.4
Water type
Freshwater
Tank level
Bottom
Adult size
40 cm
Minimum tank volume
>= 500 L
Minimum group
>= 1
GH
15 - 30 dGH
KH
7 - 15 dKH
TDS
295 - 600 ppm
Conductivity
461 - 938 uS/cm
Species description
Geographical Origin and Habitat: Indo-Pacific and Red Sea. Inhabits very shallow waters, camouflaged among coral rubble, volcanic sand and even in drying tide pools (can survive hours out of the water).
Taxonomy and Morphology: Reef Stonefish (Synanceia verrucosa). The most venomous fish in the world. It does not look like a fish, but an algae-encrusted rock. It has upward-facing eyes and a massive trap mouth. 13 rigid hypodermic dorsal spines.
Social Behavior: The living trap. It does not swim. It stays still in the same spot even for weeks, buried in the sand or among the rocks. When a fish passes by, it opens its mouth in 15 milliseconds sucking it in whole.
Coloration and Sexual Dimorphism: Extreme Camouflage. The color (gray, brown, brick red) perfectly mimics the surrounding environment. The skin is covered with spongy warts that allow real algae and sponges to grow on it. Invisible.
Care, breeding and tankmates
Aquarium Setup: Tank for slow predators (Minimum 120 cm / 48 inches). Abundant fine sand base, to allow it to bury itself, and large round rocks (among which it will camouflage). Very weak wavemakers; strong current stresses it infinitely.
Diet and Feeding: Benthic piscivore. Very difficult to accustom it to dead food. Initially eats only live fish (brackish Mollies, guppies) that pass in front of it. After long training with (long) tongs, it will accept dead whole fish moved in front of its mouth.
Water Quality: Generates very high ammonia spikes after ingesting large whole meals. Powerful skimmer essential. Prone to parasites if the water is not perfect, as it cannot swim to "shake off" the parasites.
Compatibility and Cohabitation: Devours every crustacean and fish that is not at least twice its size. Coexists only with huge Morays, large Triggerfish or giant Groupers, but there is always the risk that other fish bother it thinking it is a rock.
Aquarium Breeding: Never reproduced in captivity. Releases eggs in the open sea.
Risks and Diseases: DANGER OF DEATH (Fatal Toxin). The 13 dorsal spines contain a destructive toxin that kills tissues, stops the heart and paralyzes the nervous system in 2 hours if untreated. Tank cleaning must be done only with reinforced anti-puncture gloves, knowing EXACTLY where the fish is (often invisible).
Geographic Origin and Distribution
Indo-Pacific and Red Sea. Inhabits very shallow waters, camouflaged among coral rubble, volcanic sand and even in drying tide pools (can survive hours out of the water).
Origin
Tropical oceans and reefs
Fish profile
- Temperament
- Semi-aggressive
- Their temperament is extremely lethargic and completely solitary; they essentially act like a living rock. They do not bother other fish unless the fish fits into their mouth, at which point it is considered food. Their extreme venom requires the aquarist to exercise profound caution during any tank maintenance.
- Diet
- Omnivore
- In the wild, they are highly specialized ambush predators that feed on passing fish and large crustaceans. In the aquarium, they must be trained to accept meaty foods presented on a feeding stick, such as whole fish, shrimp, or squid. Live feeder fish or ghost shrimp may be required initially to trigger their feeding response before transitioning to dead prey.
- Life expectancy
- 5-10 years
- In a controlled aquarium environment under optimal care, Synanceia verrucosa can achieve a lifespan of 5 to 10 years. Ensuring their longevity requires maintaining pristine marine water quality and providing a species-appropriate diet. They are highly venomous and require specialized handling, which minimizes stress for both the fish and the aquarist. Providing a stable substrate and avoiding highly active tankmates will contribute to a peaceful, healthy life for this unique predator.
- Adult size
- 40 cm
- The catalog's scalar value is 40 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 40 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Synanceia verrucosa (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Solitary
- They are solitary ambush predators in the wild and are best kept singly in the home aquarium. Keeping multiple Stonefish together requires an exceptionally large tank, and they generally ignore each other. Because they offer no social interaction, a single specimen is the safest and most common choice.
- Feeding frequency
- Twice daily
- Due to their low metabolism and sedentary nature, they do not need to be fed frequently. Offering a large, appropriately sized meaty meal two to three times a week is generally sufficient for adult specimens. Overfeeding can lead to health issues and unnecessary degradation of water quality.
- Bioload
- The Reef Stonefish has a surprisingly low bioload for its size, mostly due to its extremely sedentary lifestyle. As an ambush predator, it expends very little energy and produces waste only relative to the large, infrequent meals it consumes. Standard heavy-duty marine filtration and protein skimming are fully capable of managing its waste output.
- Flow
- Stagnant
- They prefer moderate water flow that mimics the reef environments where they camouflage themselves among the rocks. Flow should be strong enough to keep detritus from settling heavily on the substrate, but not so strong that it constantly disturbs them. They rely on their camouflage rather than swimming ability to navigate currents.
- Reproduction
- Oviparous
- Breeding the Reef Stonefish in a home aquarium is undocumented and virtually impossible due to the requirements of their pelagic larval stage. In nature, they release their eggs into the water column where they drift as plankton. The logistics of raising highly venomous, microscopic fry make captive breeding unfeasible.
- Compatibility & tankmates
- This is a highly predatory fish that will consume absolutely anything it can fit into its massive, cavernous mouth. It must only be housed with fish that are significantly larger than itself to prevent them from becoming a meal. Great care must be taken by the aquarist, as this is the most venomous fish in the world, capable of delivering a fatal sting.
- Tank level
- Bottom
- They are strict, obligate bottom dwellers that spend nearly 100% of their time resting motionless on the substrate or among rockwork. Their entire survival strategy relies on blending perfectly with the ocean floor to ambush prey. They only leave the bottom momentarily to strike at passing food before immediately resettling.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 4.4 ± 0.77 se
- Resilience
- Low (4.5 - 14 years)
- Phylogenetic uniqueness (PD50)
- 0.5156
- Bayesian Length-Weight
- a = 0.01622, b = 3.05
- VulnerabilityModerate vulnerability (39 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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