“ Animal Species: Fish „
Sterlets / Sturgeon.
Size and Species
The Sterlet ( acipenser ruthenus ) is the smallest European sturgeon seen for sale. A maximum size of 4ft and 16 kg , but this is very rare and 2ft ans 1.5 to 2kg is the normal size
The Diamond sturgeon ( acipenser gueldenstaedti ) is the second fastest growing European sturgeon and can grow in excess of 8ft. but 4 ft is about the maximum
The Siberian sturgeon ( acipenser baeri ) is a quick grower and can reach 5 ft but 3-4 ft is more normal.
They donot require salt water, the species named above can be raised and bred in fresh water with no ill effects.
They do require filtered water and high oxygen levels.( Salt water holds less oxygen than freshwater at any given temperature )
They do not tolerate chemicals very well.
They need a large pond of at least 1000 gallons and flowing water i.e a pump to create a current for them, they are river fish by nature.
They will not live on koi / pond food and they are not good at feeding from the surface as they have evolved to feed from the bottom, hence the mouth underneath the head.
They need the correct food, a high protein sinking food that is made with fish meal , they are not vegetarians and cannot digest a plant based food as they lack the enzymes to do so.
Myths about Sturgeon.
None of the Sterlets / Sturgeon sold in the UK , are wild caught they are all bred on farms around Europe.
As far as I know there are no salt water reared sturgeon for sale in the ornamental market.
For one very good reason it costs to much to rear fish in salt water when you can do it in fresh water.
They will not out grow the pond , yes they will and some species will do it very quickly.
How do I know ? I am the largest sturgeon producer in the UK.
I find sturgeon to be fish like no other... absolutely remarkable. Having kept many species of fish for over 30 years, I still wonder at them. The Common Sturgeon is one of nature’s ‘living fossils’. It has barely changed since the age of dinosaurs, when it’s ancestors were one of the most common fish in the sea. As well as their interesting appearance and history, they have characteristics that make them quite unmistakable and unique amongst other fish. Sterlet are members of the Sturgeon (Acipenseridae) family. They come from the Black and Caspian seas, where they are valued as a source of caviar (their roe), as are many members of the Sturgeon family. Understand, however, when buying from garden/aquatic centres, that the name Sturgeon and Sterlet are often interchanged through design or in confusion, and you can rarely be sure exactly what you are buying. People often imagine that a sterlet is smaller species than a sturgeon, and the potential size of this fish is a major reason for people not buying it. This confusion is therefore sometimes helpful to the retailer! Also, three different (and good) retailers have told me that sterlet are baby sturgeons, so it can be seen that the name cannot be relied upon. It is therefore best, especially to the less experienced keeper, to consider the various sturgeon/sterlets as being the same type of fish. They have similar attributes, needs and characteristics. More important for the buyer to note is the type and the country of origin. IN THE WILD: Many of the common male sturgeon have a potential length of 1 – 1.5 metres. Females will usually reach 2.15 metres in the wild, and sizes of 3.5 (more than 11 feet!) metres or more were not uncommon before the days of over-fishing. They can weigh in at up to 280 kgs. They have a lifespan of 100 years or more. Males reach sexual maturity at 7 – 10 years, females at 8 – 14 years. Despite this long lifes
pan, eggs take only a few days to hatch... and a 2.5 million might be laid at one time. It might then seem surprising to hear that this fish is becoming rare in many of its old haunts. The reasons, of course, are signs of our times; over-fishing, pollution, and obstructions across the rivers (dams and weirs) that it enters to breed. The common sturgeon live in waters throughout Europe... the Black Sea and its rivers, the N. Mediterranean Sea, and around NE Atlantic coasts. Most are found in the Black Sea between Turkey and USSR. A few are caught in British waters still. They feed at the bottom of the river or sea, and therefore have their mouths situated underneath their snout, scooping up food fro the bottom rather than catching it whilst swimming. The common sturgeon is the only European type that can survive in salt water, others live in the brackish (slightly salty - mixture of sea and river) water found in river estuaries. LIFE-CYCLE: The common sturgeon will be born in a river, from eggs that stick to the river bed, after 3 – 7 days. As mentioned, he or she might have 2.5 million siblings. The newly hatched fry will be about 9 mm long, with a tail, and a yolk sac from which it feeds during early days. It will be 6 – 12 months before the young fish develops a basic shovel mouth and barbels (touch-sensitive feelers below the snout that sense prey or food). The young sturgeon continues to grow in fresh water for about three years. Rows of scutes, or bony plates, develop like armour plating along the back, flanks and under the belly. The sturgeon has far less natural enemies now than it had it early days, but this plating has remained. The fish will then leave the river estuaries to live in the sea for most of its remaining life. They feed on small creatures... worms, molluscs and small fish, foraged from the bottom. When it is time for them to spawn, they will migrate upstream into fresh water – and it is
while making this journey, heavy with eggs, or caviar, that they are most likely to be caught. They may travel up to 1000 km, often without eating. FISHING: In N. America caviar was once given away free in bars, but it is now a luxury food - a sure sign of the sturgeons’ declining numbers! The largest... the Beluga (huso huso) are found around the USSR, where 5 metre long specimens used to be caught. There, in the Black and Caspian seas, the annual catch of sturgeon exceeded 12,000 tons during recent years. Most of the adult fish live alone in the sea. Although this might be due to shortage of numbers rather than its being anti-social. Both flesh and eggs have become highly valued, and the commercial fishing has now seen to it that few specimens outlive humans any more. In some areas fishing is strictly controlled to safeguard the future of this unique creature. IN THE POND: By now most of you will have spotted a problem. These fish live, for most of their lives, in water that is slightly salty, or seawater. Our ponds are generally freshwater, in keeping with the needs of the rest of our fish and plants. The second problem that is quickly apparent is that of size. A sturgeon that remains healthy despite being in freshwater will quickly outgrow the average garden pond. Apart from the obvious addition of salt, the other difference between sea and freshwater is the higher proportion of oxygen in the former – and sturgeon need this if they are to do well. Many aquatic dealers will not sell sturgeon, or sterlet, of any kind, because of their need for brackish water. However, others do. SO what is the aquarist to do? Here is a fish that makes a stunning addition to any pond, offered for sale at about 10 cms long. The more you see them, and realise what comical and tame fish they can be, the more attractive they appear. And for obvious reasons, dealers who do sell them will tell you that their own are doing
well in freshwater. I have heard both success and disaster stories concerning their survival in ponds. I wonder if, to some degree, it depends not just on the variety, but also on the health and resilience of the individual fish in question. Ultimately, your own conscience and experience will determine whether or not you should take the chance of trying to keep them in a garden pond. Bear in mind two things. First of all, avoid buying the common sturgeon, they are more adapted to salt water, and grow larger. Secondly, the young sturgeon WILL be fine in freshwater – they have almost certainly been caught and imported at a time in their life when they would still have been living in the rivers. Whether they will continue to thrive in freshwater is, however, a different matter – and a matter where opinions differ greatly. The diamond back sturgeon, almost always called a sterlet, is smaller than the common or Siberian variety, and seems happier to be in freshwater. WHY TRY? The sturgeon/sterlet is a fascinating fish. In time it will learn to flip over onto its back to feed from the surface, but more commonly, and just as entrancingly, it will glide around the sides of the pond on edge, scooping up food that has stuck to the wall off the pond. Within a short space of time you will be able to drop food straight into its eager mouth, especially in the early evening, when it is far more active than at other times. This gentle giant is never aggressive. It will feed on little worms and fry, but it won’t harm relatively small fish. Nor will it rip plants from their containers. It is also a beautiful creature... albeit in a rather strange way. BUYING AND KEEPING: The diamond back sells for about twice the price of a Siberian specimen of similar size. I have kept mine in a large (6 feet long) tank indoors for their first few months, putting them out in the following Spring. This allows me to ensure that the
y are staying healthy and feeding well, and they seem to grow on quickly in the warmer water. They may be fed sinking pellets, which is more natural to them as they normally feed from the bottom, but once in a pond, they will need to feed from the surface if possible. Too much unfound sunken food will quickly sour the water. I have bought different species in the hope of finding the ideal, even diamond backs come in slightly different types – and the aquatic centres rarely know exactly what they have. Your hope must be that having only been used to fresh water, it will continue to thrive in it. Don’t be tempted by large specimens. Not only are they very expensive (and if yours does well, it will very soon grow), but it could well be that they were caught in an estuary or even in seawater, and are therefore used to salty water. Larger specimens of any fish tend to adapt less well to different surroundings, especially if they were once wild. Sturgeon need oxygen rich water. They are busy creatures, especially in the warmth of a big tank, or in the comparative warmth of British pond water. They also need cleaner water than the more tolerant goldfish. Make sure that you have a good filter system in operation before adding them to a pond, and mature water. A pump and aerating fountain head will improve the oxygen content of the water immensely. Remember, if your pond is small they will soon outgrow it. If it is large, then try to keep them in a tank or smaller pond until you are sure that they are feeding well. They will need food at the side of the pond, where they can easily take it. But if they are only accustomed to finding food on the bed of the water, then they will not know to find it on the surface. If they don’t learn fast, then they could suffer or even die from starvation. The dilemma of keeping fish that have been wild-caught, imported or have come from different types of water to our own is a very p
ersonal one. If you choose to take the chance, then make sure that you are giving this very vulnerable creature the best shot possible. If, at some time in his life, you see him unwell, then a little salt might be the answer – it tends to act as a tonic for all fish, in small quantity. Buy a good sea salt, and use the amount prescribed on the packet. Beware of blanket weed, the cotton wool time algae that often takes over ponds. Electronic blanket weed controllers soften the water as well as controlling the growth, and natural aids such as barley straw can also be obtained from aquarist suppliers. It is not uncommon for a sturgeon to entangle itself in this weed, and die. It is comparatively recently that this fish has become abundant in our stores, so its long term success is barely known. Be sure of one thing though. if you love fish, then this one will quickly steal your heart; and so break it if your attempt to keep it fails. Good luck!
If you want a fish that does not look like the usual goldfish or koi, then why not think about a Sterlet... This fish is a true Sturgeon, and close relative of the fish that gives us caviar. They they look like a cross between a shart and a ray, and come in I think, three varieties. There is the common variety - all black with a long snout; the diamond, which is black with silver running down it's body; and the gold spot, which is black and gold. The diamond and gold are usually twice the price of the common but shape-wise I think the common is a more handsome looking fish. At my local fish-supplier, you can get an 6-7 inch common sterlet for £8.99 and a diamond one of the same size for £19.99 Sterlets can grow quite long, averaging 24 inches depending on the size of their home, so please make sure that your pond/pool is large enough. they are bottom and side dwellers and their mouths are situated underneath. They skim along, searching for food with "whiskers" and sift the bottom for food. Ideally they prefer a sandy bottom, but pes gravel is alright. They prefer cool water and are more active in the evening when the sun is going down. They will eat regular fish food as long as you let it float - they cannot eat from a feeding ring. There are also specialist sterlet food on the market. they are also partial to the odd treat like sea monkeys or blood worms... Sterlets are very tame fish and can be stroked quite easily. Very even-tempered, mine (called Snoopy) reminds me of a "Sausage-dog" with fins instead of legs...