Just a few decades ago, encountering a tropical pufferfish in the Mediterranean would have seemed like a biological curiosity. Today, some species are a permanent part of its eastern region and are gradually penetrating into the Adriatic Sea and the western Mediterranean. The silverstripe pufferfish attracts the most attention, as its invasion poses ecological, economic, and health problems.
The silverstripe pufferfish (Lagocephalus sceleratus) originates from tropical and subtropical regions of the Indian and Pacific Oceans. It reached the Mediterranean from the Red Sea via the Suez Canal. The Suez Canal created a corridor between two originally separated marine areas, allowing hundreds of non-native organisms to spread into the Mediterranean. These include fish, mollusks, crustaceans, jellyfish, and algae. Not all can establish themselves permanently in the new environment, but the silverstripe pufferfish is among the exceptionally successful colonizers.
The first confirmed Mediterranean find of this species dates back to 2003 from the Turkish Gulf of Gökova. This was followed by rapid spread along the coasts of Turkey, Israel, Lebanon, Egypt, Cyprus, and Greece. Later, it was recorded in Tunisia, Malta, the Adriatic Sea, and even near Ceuta at the Strait of Gibraltar. CIESM currently assesses it as a very common species in the Mediterranean, especially in its eastern part.
A significant warning for European tourists and aquarists was the find in the Croatian bay of Medulin. A male measuring 52.2 centimeters and weighing 1.33 kilograms was caught here in May 2024. This was the northernmost confirmed find of the silverstripe pufferfish not only in the Adriatic but in the entire Mediterranean.
The Suez Canal itself opened a path for the fish, but their successful establishment also depends on conditions in the new environment. The Mediterranean is warming, and especially its eastern part increasingly resembles the subtropical regions of the Red Sea.
Higher temperatures prolong the period during which tropical species can reproduce and actively feed. At the same time, the temperature barrier that previously slowed their advance into the northern and western parts of the Mediterranean is diminishing. Rising temperatures promote the spread of non-native pufferfish and other warmth-loving fish, altering the species composition of coastal ecosystems.
The silverstripe pufferfish is also not a dietary specialist. It preys on crustaceans, mollusks, echinoderms, cephalopods, and smaller fish. It can move over sandy and rocky bottoms, around reefs, seagrass beds, and in harbor areas. Its eggs and larvae float freely in the water column, allowing ocean currents to transport them over considerable distances.
The body of this fish is elongated in a resting state and tapers towards the tail. The head is robust, with a blunt snout and prominent eyes. The upper part of the body is grayish to silvery and covered with dark spots. A distinct light, silvery stripe runs along the sides, and the belly is white.
The dorsal and anal fins are positioned far back and are almost opposite each other. The pelvic fins are completely absent. A typical feature is also the four robust dental plates – two in the upper and two in the lower jaw. They form a beak that the fish easily uses to crush the shells of mollusks, the exoskeletons of crustaceans, fishing lines, and parts of nets.
When threatened, the pufferfish can quickly gulp water and significantly increase its body volume. Common individuals measure approximately 20 to 60 centimeters, and according to the CIESM atlas, they can reach lengths of up to around 85 centimeters.
Other non-native pufferfish species also appear in the Mediterranean, such as Lagocephalus suezensis or Lagocephalus guentheri. However, the silverstripe pufferfish is considered the most problematic due to its size, rapid spread, feeding behavior, and high toxicity.
The most serious risk is tetrodotoxin, an extraordinarily potent neurotoxin that can be found in the liver, reproductive organs, intestines, skin, and muscle tissue of the fish. Its quantity varies among individual specimens, organs, seasons, and locations. Therefore, there is no part of the Mediterranean pufferfish that can be considered safe to eat.
Tetrodotoxin blocks sodium channels in nerve and muscle cells. The first symptoms of poisoning are often tingling or numbness of the lips and tongue, nausea, vomiting, dizziness, and muscle weakness. Severe poisoning progresses to total paralysis and respiratory failure, while the affected person may remain conscious.
The toxin is heat-stable. Common cooking, frying, drying, or freezing does not reliably destroy it. There is also no specific antidote for poisoning, and treatment mainly consists of intensive supportive care and artificial ventilation until the organism eliminates the toxin.
European regulations therefore prohibit the marketing of products derived from toxic fish of the Tetraodontidae family. The fish cannot be considered the Mediterranean equivalent of the Japanese fugu, which could be safely prepared merely by removing the internal organs.
A study published in 2024 collected at least 144 cases of non-fatal poisoning and 27 deaths from pufferfish consumption in the eastern Mediterranean between 2004 and 2023. The authors also recorded 28 cases of physical attacks or bites. The data comes from scientific literature, medical reports, interviews, and other records, and the actual number of incidents may vary.
The pufferfish is not poisonous in the sense of an animal that actively injects toxin through a sting or spine. Simply swimming near it generally does not pose an immediate danger. The risk arises primarily from consumption or very close contact.
However, its powerful teeth can cause deep wounds. Documented cases of bites have primarily involved fishermen, people handling catches, and bathers who approached the fish, attempted to feed it, or found themselves in its immediate vicinity. Attacks on humans remain less frequent compared to the risk of poisoning, but they cannot be entirely ignored.
An invasive species is not dangerous solely because it is toxic. What is essential is how it affects native communities. The silverstripe pufferfish is a strong and adaptable predator that consumes economically and ecologically significant crustaceans, mollusks, and fish.
It can thus reduce the abundance of certain species and alter relationships in food chains. In its new environment, it also has a limited number of natural enemies. Its toxicity, size, and ability to quickly occupy various types of habitats give it a significant advantage.
Here it is important to distinguish between non-native and invasive species. A non-native organism does not automatically cause harm. It is considered invasive when it successfully reproduces in a new environment, spreads rapidly, and has demonstrable negative impacts. The silverstripe pufferfish meets these criteria in the eastern Mediterranean.
The economic damage is very visible. Pufferfish chew through fishing lines, damage nets, and remove caught fish from them. The catch can be spoiled before the fisherman hauls it aboard. Since the pufferfish itself cannot be sold as food, its accidental catch represents additional work and costs without economic benefit.
Greek fishermen report damages to nets reaching thousands of euros per year for individual boats. Cyprus and, more recently, Greece have therefore introduced a program in which professional fishermen are financially rewarded (in Greece 5.33 euros/kg) for targeted catches and handing over pufferfish for safe disposal. European projects are also exploring the possibilities of industrial processing of the fish into feed ingredients, but only under conditions where the toxin is professionally deactivated.
When diving or snorkeling, it is advisable to observe the fish from a distance. It is not good to feed it, chase it into hiding, or attempt to catch it. Photographing from a safe distance can help document its further spread.
Fishermen should not taste, fillet, or give the catch to pets. When handling, one must primarily account for a quick and strong bite. The method of reporting, killing, or handing over the fish varies in different Mediterranean countries, so it is advisable to follow the guidelines of local fishing and veterinary authorities.
After a bite, it is necessary to stop the bleeding, clean the wound, and seek medical attention. If there is suspicion of pufferfish ingestion or the first neurological symptoms appear, emergency services should be contacted immediately. Waiting for spontaneous improvement can be life-threatening in cases of tetrodotoxin poisoning.
For aquarists, the pufferfish can be fascinating due to its anatomy, intelligence, and unusual defense mechanism. However, the silverstripe pufferfish is definitely not a suitable candidate for a typical home marine aquarium.
It grows to a considerable size, is an active predator, possesses an extraordinarily strong dentition, and can attack other organisms and the technical equipment of the tank. Handling a large specimen poses a risk of injury, and any potential death creates a problem for the safe disposal of the toxic body. Therefore, live individuals should not be caught or transported from the wild.
The complete removal of the silverstripe pufferfish from the Mediterranean is likely no longer realistic. The species is spread over too large an area and has established stable populations in many regions. However, targeted catches, monitoring of new finds, informing fishermen and the public, and strict control of fish sales make sense.
The story of the pufferfish also illustrates how quickly seemingly familiar marine ecosystems can change. The combination of artificially created migration routes, intensive shipping traffic, and warming waters allows tropical species to move further north. A fish that was almost unknown in the Mediterranean at the beginning of this century is now one of the most prominent symbols of biological invasion in European seas.
When I sit in front of the aquarium and capture the happenings within it. I notice that I am being observed. And so I sometimes wonder who is observing whom.
Hello aquarists and breeders!
Summer is in full swing, but that doesn't mean our tanks should be idle. On the contrary – the end of August will be an ideal opportunity to refresh the blood in your breeding stock, find rare strains of fish, or replenish your supplies of cuttings of aquatic plants after the summer season.
The Plzeň Aquarists Association IRIS warmly invites you to the Plzeň Aquarist Summer 2026, a traditional summer aquarist market, which will take place on Saturday, August 29, 2026.
Why shouldn't you miss this event?
- Directly from breeders: No anonymous imports from wholesalers. You will find a wide selection of aquarium fish, invertebrates, and plants directly from the breeders of local and distant aquarists.
- Complete assortment: In addition to live material, quality feeds (live, frozen, and dried specialties) and breeding supplies will be available at favorable prices.
- Expert advice: The IRIS Association is historically the second oldest aquarist association in the Czech lands. You will meet veterans of Czech aquaristics on site, with whom you can consult fish diseases, water parameters, cichlid genetics, or setups for demanding aquascaping projects.
- When: Saturday, August 29, 2026
- Time: 9:00 AM – 11:00 AM (We recommend arriving on time; the best pieces disappear within the first hour!)
- Location: Dormitory of the SPŠ Transport, Karlovarská třída 99, Plzeň
Do you have full aquariums of your own breeding or trimmed moss and lack space for new projects? Come show your breeding successes to others!
Reservation of sales spots: Table orders are accepted until August 26, 2026. Space capacity may be limited, so don't delay with your reservation.
- 📞 Phone: 603 231 494
- ✉️ Email: info@irisplzen.cz
If you miss regular contact with people who share the same passion for the underwater world, you have a unique opportunity. Those interested in membership in the IRIS Association can sign up directly at the event. By doing so, you will support organized aquaristics in the Czech Republic and gain access to club events and lectures.
Come chat about fish, shop, and meet old acquaintances from the field.
We look forward to seeing you in Plzeň!
The Team of the Plzeň Aquarists Association IRIS
Hello all aquarium enthusiasts!
The British Killifish Association (BKA) warmly invites you to the first in a series of summer online seminars, taking place this Wednesday, June 10th. If you are interested in killifishes, their care, color forms, or just want to gain inspiration from an experienced foreign aquarist, don’t miss this lecture. Everyone is welcome!
- Speaker: Dieter Ott
- Topic: “Fascinating Killifishes” (The Fascinating World of Killifishes)
- When: Wednesday, June 10, 2026, at 20:30 CEST (19:30 BST / GMT)
- Where: Online via Zoom
You can join the lecture directly by clicking the link below or entering the details in the Zoom app:
- Join link: Enter Zoom room
- Meeting ID: 827 0388 5789
- Passcode: australe
> 📅 Tip: If you want to save the meeting directly to your calendar, you can download the iCalendar (.ics) file here.
More information about other upcoming seminars (July, September, October) can be found on the official website killis.org.uk.
We look forward to your participation! 🐠 Feel free to share the invitation with other fellow aquarists.
Akváristé a teraristé, zbystřete! Máme pro vás skvělý tip na akci, kterou byste si letos na podzim rozhodně neměli nechat ujít. Akva-tera klub ZO ČSCH Rychnov nad Kněžnou pořádá již 47. ročník legendární výstavy AkvaEXPO 2026 RK.
Přijďte načerpat inspiraci, nakoupit do svých nádrží nebo si jen užít skvělou atmosféru mezi lidmi se stejnou vášní.
- Termín: 12. – 20. září 2026
- Čas: denně od 8:30 do 18:00 (poslední den 20. 9. pouze do 16:00)
- Místo: Dům chovatelů, Trčkova 437, Rychnov nad Kněžnou
- Velká výstava: Fascinující expozice akvarijních ryb, vodních rostlin a terarijních živočichů.
- AkvaEXPO v Rychnově nad Kněžnou není jen obyčejná prodejní burza, ale kompletní zážitek pro všechny milovníky podvodního života a terarijních zvířat.
- Nádrže budou připraveny jen těmi nejlepšími a nejšikovnějšími akvaristy!
- Tradiční prodej: Bohatý výběr ryb, krevet, živých rostlin, kvalitních krmiv a dalšího akvaristického i teraristického vybavení přímo od chovatelů.
- Přímo na místě bude probíhat velký prodej akvarijních ryb, krevet, šneků a vodních rostlin. Chovatelé zde nabídnou také kvalitní krmiva, akvarijní techniku a další chovatelské potřeby. Máte tak jedinečnou šanci pořídit vše potřebné pro váš aquascaping nebo chov na jednom místě a za skvělé ceny.
- Odborné přednášky: Možnost rozšířit si obzory a pobavit se s experty z oboru.
- Součástí doprovodného programu jsou odborné přednášky. Můžete zde konzultovat své chovatelské úspěchy i starosti s předními českými akvaristy a terarity. Těšte se známá akvaristická jména!(více zveřejníme brzy)
Výstava v Rychnově má neopakovatelnou atmosféru s téměř padesátiletou tradicí. Je ideálním místem pro setkání komunity, načerpání nové inspirace a nákup zdravých živočichů přímo z českých odchovů.
Tip pro návštěvníky:
- Pokud jedete na výstavu primárně za nákupy rostlin a ryb, doporučujeme dorazit v prvních dnech konání, kdy je výběr nejširší. Pokud chcete klidnější prohlídku expozic, zvolte pracovní dny v dopoledních hodinách.
- Akce je známá také skvělým pohoštěním, takže můžete využít posezení k diskuzi a občerstvení.
Aquarium after the renovation, how is it doing and what changes have occurred? The first photo is right after the renovation and the second one is after 1 month and 17 days. What do you think? Would you change anything?
On the banks of the Vistula, a system operates that would have seemed more like an experiment than a part of urban infrastructure just a few years ago. Warsaw utilizes freshwater mussels as living sensors for water quality. This is not a curiosity, but a full-fledged layer of protection for drinking water, directly connected to the control systems of the waterworks.
The basic principle is simple: mussels filter water, and if something harmful appears in it, they immediately close their shells. This movement, which is a matter of survival for the organism, is translated into data in Warsaw using sensors attached to their shells. The system monitors group behavior and responds to synchronous changes.
Technical Solution
Small sensors are attached to the shells, measuring their opening in real-time. Data is continuously evaluated and filtered to eliminate random behavior of individual organisms, thus the behavior of the entire group is closely monitored. Once multiple mussels begin to close simultaneously within a defined time frame, the algorithm evaluates this as an anomaly and responds by issuing an alarm. This signal is connected to the waterworks control system (SCADA), which can automatically react—such as by shutting off the water supply.
The technical implementation is simple yet precise. Small sensors are attached to both halves of the mussel, capable of measuring the distance between them with high accuracy, that is, the degree of opening. Data is transmitted to the control unit at short intervals, where it is processed. Importantly, the system does not work with a single immediate impulse. It first filters out random movements and the natural behavior of individual organisms, then tracks trends over time, and primarily compares reactions among multiple mussels.
Mussels Discover More Than Classic Sensors
Unlike traditional probes that measure specific parameters such as pH, conductivity, or the presence of defined chemical substances, mussels operate differently. They respond to the overall impact of the environment on a living organism. This means they can detect situations where an unknown substance or a combination of multiple factors appears in the water, which individually might not exceed any limits from the sensors' perspective.
In the case of contamination, mussels close within seconds, and the entire system can evaluate the situation within tens of seconds to one minute. This speed makes biomonitoring an ideal "first warning layer" that complements more detailed but slower laboratory analyses.
To maintain reliability, the system works with a group of several individuals, and their behavior is continuously calibrated. Mussels are placed in a flow chamber, where they constantly filter water from the river, and after a certain period, they are replaced to prevent adaptation to the environment.
The great thing about this is that the mussels are not harmed; they live in an environment similar to their natural habitat and are returned to nature after a few months, with their place taken by their successors.
This is what aquaristics can look like in a country where theft is practically nonexistent and rules are followed. In a residential area, there is this open aquaristics where you can choose fish or accessories and pay into a donation box.
