In our seas and oceans there is a large amount de peces with various strange shapes and all kinds of sizes. An example of this is the sunfish. Having almost no resemblance to other fish, it doesn't even look like it was a fish. Today we are going to analyze in depth a fish that is known as eels and is classified as fish. They are not snakes per se, but they look like one. Its about moray eel.
Want to discover all the secrets this curious species holds? Keep reading to find out more.
Key features
The moray eel is a large fish belonging to the Muraenidae family . As mentioned, they are commonly known as eels because they belong to the order Anguilliformes. A key characteristic of all members of this order is the absence of pectoral and ventral fins . They also have smooth, scaleless skin . This genus is quite common in the Mediterranean and is abundant in tropical and subtropical seas.
The moray eel has a rather elongated, eel-like body and can reach up to 1,5 meters in length . Its weight is usually around 15 kg, although most specimens are somewhat heavier. Its coloration varies from dark gray to brown with some fine dark spots. Its skin is slimy and scaleless, as mentioned previously, and is covered with a protective mucus that reduces friction and acts as a barrier against pathogens.
The dorsal fin begins behind its head and extends to the caudal fin, which is fused with the anal fin. They lack pectoral fins, and their long, pointed teeth are adapted for grasping slippery prey. Their mouth is long and robust, reaching behind the gills. If you observe a moray eel opening and closing its mouth, remember that this action pumps water towards the gills ; it is not necessarily a sign of aggression.
In addition to these features, moray eels have two pairs of nostrils (nasal openings), one at the tip of the snout and another above or behind the eyes, which enhance their extraordinary sense of smell. In many species, the head is narrow and does not generate powerful suction when feeding, so they have developed a unique adaptation among vertebrates: mobile pharyngeal jaws that project from the throat to grasp and move prey toward the esophagus.
Within the Muraenidae family, two subfamilies are distinguished: Muraeninae (the dorsal fin originates just behind the head, as seen in species like Muraena helena ) and Uropterygiinae (with fin bands displaced towards the end of the tail, known as snake moray eels). The family includes numerous genera, among them Gymnothorax , Muraena , Echidna , Enchelycore , Rhinomuraena , Strophidon , and Uropterygius , with a wide diversity of color patterns and sizes (some tropical species easily exceed 1.5 meters in length).
Range and habitat
The moray eel is found throughout the Mediterranean Sea . It is present in tropical and subtropical waters ranging from the eastern Atlantic Ocean, from Senegal to the British Isles . It also occurs in Macaronesian archipelagos such as the Azores and the Canary Islands , and in numerous coral reefs in warm regions around the world.
As for their natural habitat, they typically prefer rocky areas of the sea, such as coral reefs, walls, and seabeds with crevices and caves where they find perfect refuge for ambush. In the Mediterranean, they are observed between 5 and 80 meters deep, although most sightings are concentrated in relatively shallow waters. In summer, they may approach the coast more closely, while in colder waters they tend to occupy somewhat deeper areas.
The Mediterranean moray eel lives a solitary and territorial life . They tend to defend their home territory and are nocturnal . It is common to see them poking their heads out of their hiding places, sometimes in association with conger eels ( Conger conger ) or in the presence of cleaner shrimp such as Lysmata seticaudata . These shrimp form a mutualistic symbiosis , removing food debris and parasites from the moray's skin and oral cavity.
The reproduction of this fish is not well understood, so we won't be able to cover it in this post. The only thing that is known is that they produce a large number of eggs during spawning. Nearly 60.000 eggs, for example. Because there are so many, they are prone to parasites such as trematodes. Folliculovarium mediterraneum and the flatworm Lecithochirium grandiporum. In addition, it is de peces oviparous and the larvae, called leptocephalusThey are transparent and pelagic; they spend weeks or months drifting before metamorphosing and settling to the bottom.
Possible confusion in the Mediterranean
The Mediterranean moray eel ( Muraena helena ) has a very distinctive brown pattern with yellow and black spots . It is difficult to confuse it with the tiger moray eel ( Enchelycore anatina ), which has an orange hue and very visible teeth, or with the common moray ( Gymnothorax unicolor ), which is more uniformly brown.
Relationship with fishing and culinary value
Although not a commercially important species, it is caught sporadically. The most effective method is with a harpoon , locating specimens in their burrows; it also takes lures in rockfishing and baits in surfcasting . Historically, in Roman times , it was highly prized in gastronomy and was raised in coastal fish farms. Today, its consumption is more limited and depends on the region (for example, in some Atlantic island areas). With large tropical species, caution should be exercised due to possible bioaccumulation of toxins (e.g., ciguatera); traditionally, its flesh has been prepared marinated or cooked.
Food
This species is carnivorous and a scavenger . During its active period, it hunts other fish and cephalopods. Occasionally, it can be found hunting other moray eels. Its eyesight is not very good , so it relies primarily on its sense of smell to track its prey.
It is a scavenger when it cannot find other types of food. This animal is an apex predator at the top of the food chain on its reefs. It is capable of eating other animals relatively larger than itself, especially in confined spaces where its muscular and flexible body allows it to maneuver effectively.
What puts the moray eel at the top of the food chain is that it is a powerful predator. Its jaw has a highly developed system consisting of a second jaw that opens when the first one is already open.
To feed, it grasps its prey with its first jaw and pulls it outward, clamping down on the prey. These jaw adaptations make the moray eel a formidable biting machine . Most fish rely on opening their large jaws rapidly, using negative water pressure to suck their prey into their mouths.
This is the eel's ability to swallow large fish and creatures whole. Additionally, some moray eels use the tail-knotting technique to tear chunks out of bulky prey (for example, octopuses). Cleaning relationships with shrimp ( Lysmata seticaudata ) are common, with the shrimp removing food debris from their mouths and skin. Cooperative hunting with groupers has also been documented on tropical reefs, where both predators benefit.
Brown fish in captivity
As you can imagine, it's quite difficult to keep a fish with these characteristics in aquariums . However, it's not impossible. Following certain recommendations is necessary to ensure the fish lives a healthy and peaceful life. This species is only recommended for those with advanced experience in the world of aquariums.
They are prone to skin diseases . Lacking scales, they are extremely sensitive to many medications, and when transported from their natural habitat, they can carry numerous parasites. To prevent this, it's best to quarantine them . Parasitism can be alleviated with a good UV sterilizer in the tank. This will not only help prevent many diseases but will also provide greater stability to the aquarium.
Regarding its behavior, it is a fairly calm fish that does not usually bother the rest of the aquarium companions. But nevertheless, black moray fish can become aggressive with members of their own species and others that are similar. Other than that, they are generally quite shy. You have to be careful about housing other species de peces too small compared to them, since with the such a big mouth that has available can swallow and swallow them without any problem.
Observe how it behaves with other fish; you can keep it with fish of a similar size.
Practical aquarium requirements
- Volume and cover: spacious aquariums with plenty of rocks and caves; for medium-sized moray eels, more than 400–500 liters. Essential airtight lid or safe grid: they are excellent escape artists.
- Parameters: in marine, stable salinity and powerful filtration with good movement; in estuarine or freshwater species, many actually require water brackish in its adult phase.
- Feeding in captivity: offer quality meaty prey (fish, squid, shrimp), 2–3 times per week, avoiding overfeeding. It is not recommended handfeeding; use long tweezers.
- Companions: fish of similar or larger size, avoiding invertebrates that could be preyed upon. Monitor for conflicts with species with similar shape (conger eels, other moray eels).
Diseases
Diseases can affect these fish, although they don't usually cause much trouble if the aquarium is well cared for and maintained. River moray eels are even more prone to disease than saltwater moray eels. If we notice any symptoms of illness, we should quarantine the fish and isolate the tank. They may float to the surface to soothe their skin when they feel very irritated or stressed.
They generally respond well to many medications and heal quickly. Never use copper in a river eel tank, or it could cause infection. In general, copper-based drugs and other harsh treatments are not well tolerated by scaleless fish; consider alternatives such as praziquantel for trematodes, controlled baths, or environmental management (improved water quality and UV lighting).
When keeping multiple fish together, it's common for them all to be infected even before the first warning signs appear. The best way to prevent disease is to provide the fish with a suitable environment and a well-balanced diet. Among the most common diseases in moray eels are:
- External parasites (trematodes and nematodes) and protozoa on the skin and gills; observe rapid breathing or rubbing.
- Bacterial infections secondary to bites or rubbing against rocks, which cause redness and ulceration.
- Osmotic stress due to inadequate salinity in brackish species, which depresses the immune system.
- Nutritional deficiencies by monotonous diets; alternating types of fish and cephalopods of good origin.
A properly sized UV sterilizer, regular water changes, stable parameters , and preventative quarantines are the best insurance policy for your health.
https://www.youtube.com/watch?v= rLd4FedXUnY
Although its appearance is imposing, the moray eel is a fascinating fish: eel-like, nocturnal, and stealthy , a keystone species of reefs and rocky bottoms. Recognizing its characteristics (lack of pectoral fins, protective mucus , sharp teeth, and pharyngeal jaws ), understanding its habitat , and knowing how to feed and care for it in captivity will allow you to enjoy it safely, whether diving or in an advanced aquarium. Respecting its space, avoiding touching it, and maintaining stable aquarium systems minimizes risks and enhances its natural behavior.