Freshwater stingrays are said to be one of the most challenging species to keep. Not only does most of them grow relatively large, but they are also very sensitive to elevated levels of waste in the water.
Here i will share some of my knowledge and experiences with these fishes. Hopefully this article can form a sort of starting point, and be of help to those out there who want to give freshwater stingrays a try.
First and foremost, – avoid spontaneous purchases! It is important to look ahead and to consider if you have room to house them as they grow. If you dont have the space to house a fully grow specimen at present day, one should at least have serious ambitions for later upgrades. Several of the species could potentially be up to 80-90 centimeters around the disk.
Rays have a very fast metabolism and need a lot of food to achieve a natural and healthy growth. The bio-load in the aquarium will therefore be pretty heavy, which suggests that one is forced to run with good circulation and adequate filter media. It is hard to give a definitive answer regarding size of the filter etc, since it varies based on the different factors and influence – such as water volume, turnover-rate, type of filter media, interior design, number of fish, the amount of food provided, etc. But my best advice would be to over-compensate – add a bit more filtervolum and filtermedia that you usually do with other setups.
It is extremely important to make shure the filter is sufficient, to avoid the build-up of waste (ammonia and nitrite). This of course also applies for other fishes, but the rays are usually the first to get problems if the water chemistry is not in balance.
It`s worth mentioning that you should avoid exposing the stingrays for high nitrate valuesover time as it potentially could weaken their immune system, and this of course makes them less resistant to disease.
When you get your first stingray – feed carefully at the start and take regular water samples. After some time you will then find out what water-change regime you have to set – to keep nitrate levels down. It`s a good idea to keep a small notebook where you put in the date of water-changes, water parameters, etc.
Do not be surprised if it turns out you need to replace 50-80% of water every 4 day to maintain the nitrate value.
If the bio-load in the aquarium is heavy – and your filter capacity isn`t sufficient – you can potentially get to a point where the bacteria are unable to cope with all the waste fast enough. The result would be increased levels of ammonia in the water (the toxicity depends on the pH and temperature), and/or nitrite. «Overloading» is clearly the most common reason people fail with the stingrays.
When the rays get exposed to high levels of nitrite (remember – anytime ammonia levels are elevated, elevated nitrites will soon follow, if not already present), this is usually reflected in distinct bruising on the mouth opening and the rectal gland, and also around the gills. Others symptoms could be listlessness, heavy/rapid breathing, and increased production of mucus. The appetite will also be affected, more or less.
If you are in a situation where the ray has been exposed to ammonia or nitrite, the first thing to do is water-change. But this is not always enough, and salt can be a lifesaver in such cases. Nitrite block the blood’s ability to transport oxygen – it binds to red blood cells. Reputedly the right concentrations of salt will actually be able to prevent the nitrite from binding. I have saved both rays and other fishes – that have been exposed to potantial poisoning – by the addition of salt. I have found that a dose of 4 heaped tablespoons per 100 liters will help – at 0,3 mg/l nitrite (does in the course of two days).
Many people say it is very important to dissolve the salt in water before adding, to avoid the concentrated salt to come in direct contact with the stingray. But i have always added the salt without doing this, and despite the fact that the rays sometimes have comed in contact with it – i have never observed any negative consequences from this. (Of course you don`t need to pour it right on top of them).
It is not only a «bio-overload», which can kill the dream of success. In spite the fact that stingrays spend a lot of time searching for food in the substrate – turning it over many times a day – it is nevertheless important to remember that sand potentially can be a trouble maker. Food items that are not eaten, can potentially be buried in the substrate, where they will be rotting – cousing problems!
How big the chance is for this to happen depends – among other things – of how thick the layer of substrate is, and how large the bottom-area is – in relation to the size and movement pattern of the stingray. Not to mention the number of rays you have. The decor can also pose a risk, if it prevents the ray from digging in given areas.
When a piece of un-eaten food are baried under the substrate, it will not be break down in a effective way. Couse under the layers of sand it is too little oxygen for good aerobic bacteria to thrive.
The water parameters can be fine, and things may seem very good, but when the stingray suddenly dig up such an area – where the sand has been immobile for some time – they can be directly exposed to hazardous wastes.
It is therefore important to observe – to make shure to avoid that sertant areas get «packed».
My tip is to use sand in small quantities – for the less sand you have, the less the chance that it packs up (remember that the substrate and the interior should not have sharp edges). I prefer to use river-gravel, couse it is «airy» and thus it also has some value in relation to the biological filtration of the water.
Many people choose to keep the rays in aquaria without substrate for simplicity’s sake, but personally I think this is a bad and unworthy way to keep such a fish. Can you imagine anything more unnatural for an animal that typically use all day to mess in the bottom materials in search of food? I have keept my stingrays on bare-bottom a couple of times, of different reasons, and i have observed clear signs of dissatisfaction and stress.
Freshwater Rays, of course, like all other living beings available for certain types of diseases and parasites. The problem with stingrays is that they generally are not tolerant of the common drugs found in the stores. There are some types that are ray-safe, but there are very few. I recommend searching around on the internet about this.
Drugs that i know of that can be used against internal parasites is Prazquantel and Levamisole. I have used both multiple times. In the case of fungi and/or wounds, you can get a long way with just keeping up the water changes, and add salt. Or you can use API Pimafix. I have no experience with than one my self, but know that is is used by other ray-keepers.
Dont forget the old rule of thumb; Prevention is better than cure. The clue is to have good rutines in relation to water changes and cleaning in general, and check water parameters on a regular basis. This way you will avoid problems, given that you fishes are healthy and free from any parasites.
As mentioned, the Rays have a high metabolic rate, and it is therefore essential that they get relatively large amounts of good quality food. The natural diet consists of various crustaceans, snails, insect larvae, nymphs, and fish. Menu in captivety may include for example market-shrimp, mosquito larvae, mussels, pollock, earthworms, snails, smelt, mysis, home made mixes with added spirulina/vitamines/carnivore pellets etc etc.
There are many different types of stingrays available on the market, and the price varies widely. While some individuals can cost you up to 5000 $, there are cheaper alternatives. P.reticulata is perhaps the most common in the trade. They also goes to be one of the most difficult rays to keep, for some reason.
These are usually wild-caught and have a long journey behind them. The stress this causes often results in that they are very thin and malnourished – which of course leads to a weakened immune system – which is a very bad starting point for a stingray (or any fish for that matter).
If you buy wild-caught specimens (reticulata or any other type of stingray), be aware that there is always a risk that they could carry parasites. And when the fish is weakened – these parasites could get the upper hand.
Unfortunately P.reticulata achieves a very low price on the market, usually under 150 $. That is so cheap that most people can afford it withoutfurther questions, and many are then willing to give it a try – perhaps in spite of the lack of knowledge. This usually ends with death, and people then seems to tag them as «impossible/extremely hard to keep in aquariums».
I would recommend bying a captive bred ray from a private breeder for starters. Before you buy an individual – regardless og wild caught or captive bred – it is still wise to ensure that they eat well before you purchase. If it is a wild caught specimen, you should ask the seller what they have been eating during the quarantine period.
If you can see the hip bones on a stingray, this is a clear sign that it is malnourished. That does not mean they’re doomed, but it is a clear sign that the given individual has experienced a lot of stress over time.
Pregnant Potamotrygon wallacei;
If you have basic knowledge about the nitrogen cycle, and understand the importance of having an efficient bacteriological filtration system, and to make routine water changes, then you have good base to get a long way towards a successful husbandry of stingrays.