Leopoldi Stingrays


The Leopoldi Stingray is a species of fish in the Potamotrygonidae family endemic to Brazil. Its natural habitat is rivers. Like other members of the genus it inhabits a variety of biotopes. These include sand banks, the shallows of major rivers and slow-moving tributaries with substrates of mud or sand. It also moves into areas of flooded forest during the annual wet season and can later be found in terrestrial lakes and ponds formed by the receding flood waters.

Stingrays are so-called for their serrated, dagger-like stinger located on the top of and lying flat towards the end of the tail. Usually sheathed in a layer of skin and not always easy to see, this effective defence weapon is made of a protein, and is accompanied by a nasty venom usually released when the skin sheath of the stinger is ruptured. If the stinger cuts you it can cause large local blisters and intense burning throbbing pain.

Symptoms experienced when stung

  • The person feels immediate, sharp, excruciating pain that peaks in 1-2 hours
  • The wound bleeds
  • The wounded area may become swollen and may turn blue or red
  • Lymph nodes may become swollen
  • Nausea
  • Vomiting
  • Fever
  • Chills
  • Muscle cramps
  • Tremors
  • Paralysis
  • Fainting
  • Seizures
  • Elevated heart rate and decreased blood pressure may develop


  • Flushing the wound with fresh water
  • Scrubbing the affected area with soap and fresh water, and removing all stingers with tweezers.
  • Soaking the affected area in hot water (as hot as can be tolerated without causing burns) can help relieve the pain.
  • Since there is a strong likelihood of infection developing in the wound area, antibiotics may be prescribed along with medications for pain control.


However, these big, scary, dangerous stingrays are actually quite stunning and safe to keep in an aquarium. Leopoldi rays are a fresh water species, which in turn makes maintenance a lot easier and water chemistry a lot simpler. Leopoldi rays can reach a maximum size of 24 inches / 60 cm and prefer a pH range of between 6.0 – 6.8.

In the wild these rays would feed primarily on other fish and invertebrates, including worms and crustaceans. They’re active fish with a high metabolic rate and as such will need feeding at least twice a day. They’re also notoriously big eaters and it can cost a fair amount of money to keep even a single ray in good health, but it’s well worth it. In general, an exclusively meaty diet is preferable, such as muscles, prawns, fish etc. Some will also learn to accept dried foods.

Unlike other animals we find in the aquatic shop, gender identification is pretty simple with these guys. Just like their relatives, the Sharks and Marine Rays, male Leopoldi rays have a pair of sexual appendages known as “claspers”, one on each pelvic fin. These are used to inseminate the female when mating and are clearly visible, appearing as finger-like extensions extending backwards from the inside of the fin. In young males they’re much smaller, but can still be seen if you look closely.

Rays can be quite picky when it comes to choosing a mating partner. Simply buying a pair of rays and putting them together will not guarantee a successful breeding pair. The ideal way to obtain a pair is to buy a group of juveniles, housing them in a huge tank and allowing them to select their own partners. The spawning act itself is quite brief, lasting only a few seconds. Fertilisation occurs internally, the male inserting one of his claspers into the cloaca of the female before releasing his milt. Following a successful mating event the male should stop harassing his partner. In captive environments, rays generally gestate for between 9-12 weeks. During the latter stages the developing young can sometimes be seen as a visible lump rising from the posterior end of the female’s back, although in well-fed specimens this can be tricky to spot. It’s essential to feed the female in sufficient quantities during this period as she will expend a lot of energy providing for her pups, and her appetite will increase significantly. The pups usually have a small yolk sac attached at birth, and they will feed from this for anything up to a week. After the sac has been absorbed they should be offered high quality live and frozen foods several times a day.

Like other freshwater stingrays, Leopoldi rays have keen eyesight. Their protruding eyes allow them to see what is above them while they are on the river bottom and also help them to navigate through their murky environment. They also possess ampullae of Lorenzini (special sensing organs called electroreceptors, forming a network of jelly-filled pores) located on their skin around the nose and mouth that allows them to detect minute electric fields generated by other living organisms. This sensory detection warns them of potential predators and prey.

Overall, these animals are amazingly intelligent and a pleasure to keep. Our customers who are privileged enough to keep them think of them as one of their family and, with our help, take the greatest of care of these amazing animals.

We are lucky enough to be involved in a Leopoldi stingray breeding project and have a breeding pair of rays. Take a look at our YouTube video to see the breeding ritual of the male and female rays as he tries to bite the female ray to encourage her into submission – quite normal for sharks and rays, but I wouldn’t try it at home 🙂

Authored by Jack Riley, Aquatic Technician at Aquatic Gems Ltd



Gouramis make a great addition to the community tank! They come in a variety of different colours and sizes. If you’re looking for a fish that is slightly bigger compared to most other community tropical fish then the gourami is perfect. Some gouramis can reach up to three inches and others, such as the dwarf gouramis, will not grow bigger than one inch in size. These fish are easy to keep and get along with pretty much everything else within the community tank.

Gourami species are usually easy to breed in aquariums. All Gourami species are egg-layers, and several species are renowned for building very beautiful bubble-nests in which they keep eggs and fry. The Male Gourami will blow bubbles at the surface of the water and create a home for their young. Once the male has fertilised the female’s eggs, she will lay them and the male will pick these eggs up and place them in to his newly formed bubble nest. The Gourami is able to build these beautiful bubble nests because they have an organ other fish don’t: it’s known as ‘the Labyrinth Lung’. This allows them to breathe oxygen out of water, rather than extracting it from the water. So when oxygen levels are low in slow-moving murky water in the wild, they are still able to survive.

Click here for a video of Honey Gouramis building a bubble nest.

Authored by Jack Riley, Aquatic Technician at Aquatic Gems Ltd


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Many of us are put off by the thought of keeping seahorses, mainly due to the fear of the unknown. We hear horror stories of how difficult seahorses can be to keep successfully, that they are so susceptible to disease & infection and that they are such fussy eaters! But with the right equipment and knowledge these mythical looking creatures can make a great attraction to the salt-water aquarium.

Seahorses are relatively lower on the evolutionary scale than most bony fishes, and there are a few differences you should know that will affect how you keep these animals. First, and perhaps most importantly, seahorse gills are less efficient than those of other bony fishes. Their method of gas exchange is limited in comparison. Also, seahorses lack true stomachs. Food passes through their digestive systems with surprising speed. Because of this, they have to eat more often to maintain their energy levels.

Seahorse keepers should also keep in mind that seahorses lack scales. Instead, their structure is based on an exoskeleton that is covered with skin like tissue. Because of this, seahorses are sometimes more prone to bacterial or viral infections, so the aquarist should watch for sores on their seahorses’ skin.

Authored by Jack Riley, Aquatic Technician at Aquatic Gems Ltd

A day in the life of….Jack (Aquatic Technician for Aquatic Gems Ltd)

My morning starts with a short meeting at Aquatic Gems Ltd discussing what’s booked in for the day and also about other projects and how they’re moving along. I then gather the things needed for the day and head out. Each day is different: from maintaining a large number of different types of aquariums to selecting and introducing new fish in to them.

Once arriving at a maintenance job I check the system, making sure it’s all running correctly and that the livestock are well and healthy. I then perform a variety of water quality tests, make adjustments as needed and record these on a chart, which are then compared to the results from previous visits. I then go on to clean the tank so that it is visibly clean throughout. Once this is done I move on to the partial water change and the clean out of the filtration and replacement of any old filtration materials. After topping the tank back up accordingly I check over everything to make sure, once again, that it is all working perfectly. Tanks do differ so the process can change slightly, but the general principles still apply.

From time to time I’m involved with the installation and bespoke build side of things, as well as installing smaller pieces of equipment to established aquariums e.g. air pumps, internal/external filters, skimmers, reactors etc. I also work alongside Cem on some of the bigger installations such as through-wall aquariums and other bespoke build systems.

One of the projects I have most enjoyed working on is the Leopoldi Stingray breeding project. We are privileged to work with these beautiful, intelligent animals. A video of male and female rays courting each other can be viewed on our YouTube channel. Blog on this coming soon.

Keep reading the blog for more of Jack’s posts, as well as A Day in the Life of….Cem our Managing Director.


What is made 90% of water, has no respiratory system, no central nervous system, NO BRAIN! And is 650 million years old? ….. The Jellyfish!

Quite unbelievable facts when you think about it, and yet the jellyfish thrives and populates our oceans in vast numbers still to this day.

Jellyfish are probably some of the most unusual and mysterious creatures that you’ll ever encounter. With their gelatinous bodies and dangling tentacles, they look more like something from outer space than a real animal.

Jellyfish first appeared about 650 million years ago (before the dinosaurs!!) and are found in every ocean, from the surface to the deep sea. Some are also found in fresh water.

Jellyfish do not have a respiratory system since their skin is thin enough that the body is oxygenated by diffusion.

Jellyfish do not have a brain or central nervous system, but rather have a loose network of nerves, located in the epidermis, which is called a “nerve net.”

Moon jellies make a great spectacle within the home aquarium! With a jellyfish specific system, you can even have lighting that penetrates through the jelly causing it to slowly change colour as they glide through the water.


Authored by Jack Riley, Aquatic Technician at Aquatic Gems Ltd