STONEFISH: CHARACTERISTICS, HABITAT, FEEDING, STING, REPRODUCTION - BIOLOGY - 2025

The stonefish (Synanceia horrida), also known as estuarine fish stone is a poisonous fish that is part of the Scorpaenidae family. Its greenish-brown coloration and warty skin give it a rock-like appearance.

This allows it to camouflage itself and thus go unnoticed at the bottom of the reefs where it lives, being ideal for escaping threats and also for capturing its prey using the surprise factor.

Stone fish. Source: SeanMack

The body of Synanceia horrida is round in shape and measures up to 60 centimeters. As for the head, it is broad and depressed. Their eyes are small and set very far apart. In addition, they are located very high on the head and are directed upwards.

On the dorsal fin it has 13 to 14 spines. These are sharp, strong, ridged and erectile. Each is housed in a thick-skinned sheath, and has a poisonous gland at the base. In relation to the pectoral fins, they are large and fleshy.

Synanceia horrida is found in the marine waters of the western Indo-Pacific area, living near reefs and rocks.

characteristics

The skin

Stonefish skin is greenish or reddish brown, without scales and is often covered with filamentous algae. Its texture is irregular, due to the numerous warty bumps it has. This particularity gives the fish a rocky appearance, which allows it to camouflage itself among the stones and the reefs.

As for the coloration, it can be from brownish gray to reddish or greenish brown. These tones facilitate the integration of the fish to the rocky environment.

Behavior

This species is sedentary. During the day, most of the time it is immobile, on the sandy bottom. On the contrary, at night it is more active, moving frequently over the reefs.

When the estuarine stonefish is faced with a threat, it hides. For this, it uses vigorously shaking its huge pectoral fins and creating a shallow depression on the seabed. Then, he scoops up sand and piles it on the sides, leaving his body covered halfway.

Poison

Synanceia horrida is considered the most poisonous of fish. Numerous works have identified the components of this poison. Experts point out that it contains verrucotoxin, glycoprotein, hyaluronidase, arginine, proteinase and phosphodiesterase, among other compounds.

Likewise, the results indicate that this toxic substance is less complex, compared to that of other poisonous animals. Also, it has a number of unique proteins, not identified in other poisons.

In addition to having a hemolytic activity, the toxin has other biological repercussions. These include edema induction, endothelial vessel relaxation, hypotension, platelet aggregation, and vascular permeability.

In the presence of a predator or when the fish feels disturbed, instead of fleeing, it stays still and raises the dorsal fin. If the threatening animal collides its body with that of the fish, the spines inoculate the poison. The poison affects the neuromuscular and cardiovascular systems, and can be fatal to the victim.

Habitat and distribution

Distribution

Synanceia horrida is widespread in the marine waters of the western Indo-Pacific region, spanning north to China and from India to Australia. Thus, it is distributed in India, the Philippines, China, Papua New Guinea, Vanuatu and Australia, Also, the stonefish inhabit small island countries, such as Fiji and Singapore. In addition, it is located around Australia, in the Great Barrier Reef, Queensland, Shark Bay, Coffs Harbor and in New South Wales.

Habitat

Regarding the habitat, it is found in tropical marine or estuarine waters, in rocky or sandy areas. This species prefers to live on or around coastal coral reefs, in estuaries, near rocks or on the seabed. Another area where it can be found are the seagrass beds.

Likewise, rockfish, as it is also known, occurs on muddy, sandy or silty bottoms, usually around rock cover. These areas are perfect to go unnoticed and thus be able to attack your prey in a surprise way or to escape threats.

Synanceia horrida inhabits from very shallow tidal pools to depths of 40 meters. This tendency to live in shallow water makes it much more dangerous for man, since it is in an area accessible to swimmers and divers.

Relationship between poison production and food

The manufacture of the poison can represent a high energy cost for estuarine stonefish. This is why a group of scientists conducted an investigation to establish the possible relationship between the rate of poison production and the frequency of feeding.

In the experiment, one group of fish of this species was subjected to intermittent periods of starvation for four weeks, while the other was fed daily. Later, the experts analyzed the differences in terms of the weight of the venom between both groups.

The results indicate that the nutritional suspension significantly affects the amount of poison produced. However, this factor does not influence the quality or the components of the toxic substance.

Taxonomy

-Animal Kingdom.

-Subreino: Bilateria.

-Filum: Cordate.

-Subfilum: Vertebrate.

-Infrafilum: Gnathostomata.

-Superclass: Actinopterygii.

-Class: Teleoste.

-Superorden: Acanthopterygii.

-Order: Scorpaeniformes.

-Suborder: Scorpaenoidei

-Family: Scorpaenidae.

-Gender: Synanceia.

-Species: Synanceia horrida.

State of conservation

Stonefish populations are declining, which is why the IUCN has classified this species within the group of animals at low risk of extinction. However, said international protection organization recommends attacking the factors that are causing their decline.

Among the main threat is its capture, to be commercialized in the international markets of Japan, China and the Philippines. In these countries, its meat is considered a delicacy, which is why it is part of the exotic cuisine of various regions.

There are currently no specific conservation measures in place to prevent the poaching of Synanceia horrida. However, some areas of its distribution overlap with existing marine areas.

Feeding

Rockfish is a carnivorous animal, feeding mainly on small fish, cephalopod mollusks, shrimp, and other crustaceans. Due to the small size of the animals that make up its diet, experts point out that this species uses its venom only as defense and not to capture its prey.

To hunt, it acts as an ambush predator. Thus, it remains without moving on the seabed, often partially buried in mud or sand, next to a rock, a reef or other rocky structure. With the texture and coloration of the skin, this technique makes the fish indistinguishable from the surrounding environment.

The stonefish can wait patiently long hours, until the crustacean approaches. At that moment, she quickly opens her mouth, swallowing the food in one bite. Due to the combination of high speed attack and excellent camouflage, the prey loses any chance of escape.

Reproduction

Synanceia horrida is generally a solitary fish, so it is rarely grouped with others of the same species. The exception to this behavior is the reproductive season, where groups of stonefish seek each other to mate.

During the reproductive process, the female swims the entire length of the seabed, while laying her eggs. This leaves a thick, gelatinous layer about 60 millimeters thick, made up of eggs that have not yet been fertilized.

The eggs measure approximately 1.5 millimeters, representing a large size, compared to those of the vast majority of other species of marine fish.

The mating ritual is completed by the male rockfish. It swims over the eggs and releases its sperm. Thus, it fertilizes them and the process of development of the embryo begins.

Due to the large dimensions of the eggs, when they hatch, they produce mature young. They have a high probability of being excellent swimmers and feeding within 24 hours of being born. In this way, their chances of survival are high, compared to the larvae of other fish.

Stings

When a person approaches stonefish, they act differently than most fish. This species does not swim to escape the threat, on the contrary, it remains immobile.

The sting can occur while the person is diving or while bathing on the beach. The person could even have physical contact with the animal outside the sea, where this fish can live for up to 24 hours.

The injury caused by S. horrida causes intense pain and great swelling in the area where the fish introduced the spine with the poison. If not treated in time, the body's reaction to the toxic substance can cause shock, paralysis, and even death.

Symptoms

The symptoms will depend on the amount of poison that was inoculated and its toxicity is associated with the number of spines that were stepped on and the force that was exerted with the foot.

The sting produces a sharp and intense pain, which is located from the pelvic limbs towards the abdominal region and from the arms towards the head and neck. As for the initial symptoms, they are pain and edema in the place where the thorn penetrated.

In addition, dizziness, headache, muscle weakness, dyspnea, nausea, hypertension, and tissue necrosis occur. Shortly after the event, fever, joint pain and bacterial infection in the wound may appear, as a result of not having been treated in a timely and correct manner.

Effects edit

The poison affects various organ systems. For example, it causes shortness of breath and impairs the functions of the circulatory system, causing an irregular heart rate, fainting, and low blood pressure.

At the skin level, the wounded area bleeds and the pain produced quickly spreads to the entire limb. Also, the area around the bite changes to a lighter color. This is because oxygen in the injured area decreases, causing it to turn white.

Symptoms related to the digestive system include severe abdominal pain, diarrhea, vomiting, and nausea. In addition, the person who has suffered the stonefish sting may experience delirium, muscle spasms, fainting, seizures, headache and paralysis.

Treatment for the sting

When a S. horrida bite occurs, the most important thing is to go quickly to the nearest medical center. However, while the person is going to the hospital, some first aid actions can be taken.

First, some doctors suggest applying a loosely fitting tourniquet a few inches above the wound. Then the area should be washed with clean, fresh water. Subsequently, any residue, such as sand, is removed from the wound.

An important recommendation is that the puncture area be soaked or soaked in water as hot as possible, for 30 to 90 minutes.

In 1959, a group of experts developed a specific antidote that works against the dangerous toxin produced by stonefish. This has allowed many people to save their lives, since the poison is lethal.

References

1. Wikipedia (2019). Synanceia horrida. Recovered from en.wikipedia.org.
2. Dianne J. Bray (2019). Synanceia horrida. Fishes of Australia. Recovered from fishesofaustralia.net.au.
3. Ziegman R, Undheim EAB, Baillie G, Jones A, Alewood PF. (2019). Investigation of the estuarine stonefish (Synanceia horrida) venom composition. Recovered from ncbi.nlm.nih.gov.
4. G. Fewings, LC Squire (1999). Notes on reproduction in the estuarine stonefish Synanceia horrida. Recovered from spccfpstore1.blob.core.windows.net.
5. Jorge Field-Cortazares, Roberto Calderón-Campos (2010). Rock Fish Sting. Recovered from medigraphic.com.
6. Motomura, H., Matsuura, K., Khan, M. (2018). Synanceia horrida. The IUCN Red List of Threatened Species 2018. Recovered from iucnredlist.org.
7. Saggiomo SL, Zelenka C, Seymour J. (2017). Relationship between food and venom production in the estuarine stonefish Synanceia horrida. Recovered from ncbi.nlm.nih.gov.