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School Aquariums

Several Frontier School Division and other Manitoba schools currently participate in an experimental attempt to raise lake sturgeon in aquariums. When we first started, we knew that this would be extremely difficult; in fact most of the advice that we received was that it would be impossible. Over the years we learned a lot about sturgeon and also learned a number of lessons about aquariums. The lessons learned allowed the sturgeon program to expand into many more schools, and the small sturgeon to thrive.

Care and Feeding Of Sturgeon

Adding the Sturgeon to the Aquarium

• Sturgeon fingerlings are brought, in September, from the Grand Rapids Fish Hatchery to Frontier School Division Office in Thompson There they are placed in a large aquarium (150 gallons) to slowly acclimatize them to warmer, room temperature water and to eating blood worms which they will be fed all winter. From the aquarium in Thompson they will e distributed to all the schools involved in the Sturgeon Project.

• Sturgeon fingerlings are usually shipped in a large plastic bag, which has been inflated with pure oxygen. Because they are now from an aquarium, (in Thompson) they should already be near the same temperature as the aquariums in the schools. Sturgeon, like all fish, cannot tolerate sudden changes in water temperature. The plastic bag of sturgeon fingerlings should be placed in the aquarium and left for about 30 minutes so that the temperature can equalize. After that time, check the temperature of both the aquarium and the bag. If they are within two degrees Celsius, pour the sturgeon from the bag into the tank.
Feeding

•The sturgeon will be fed bloodworms. Bloodworms are the natural food in the wild. They are the aquatic larvae of a mosquito like insect, which may occasionally be seen in large clouds along rivers or lakes. Unlike mosquitoes, they do not bite.

•For the first four weeks sturgeon should be fed three times per day. On weekends feeding only once or twice is acceptable, but they must be fed every day! Sturgeon, which “go off”, their food will starve to death over a period of weeks. Remember to feed them only blood worms as we have found that sturgeon have proved to be very unique in their eating habits. Once they are accustomed to bloodworms they will eat nothing else and will starve, rather than eat some other foreign (to them) food material.

•For five or six fingerlings, start with one cube (approximately a teaspoon) of blood worms at each feeding. Thaw the frozen bloodworms in a cup of aquarium water. Once it thaws, pour off the stained water and the little broken bits, which float up. Throwing this waste material out makes it easier to keep the aquarium clean and the water clear. Then, add more water and pour the bloodworms into the aquarium.

•To avoid plugging the filter by sucking food through the intake, turn it off during feeding. Do not forget to turn it back on! The sturgeon may die if the filter is left off over night.

•The sturgeon will eat only a certain amount of food at each feeding. After about fifteen minutes they have eaten all that they are going to eat and they will ignore the leftovers completely. They will eat again only when they get a fresh feeding. The main disadvantage to using fresh food is that it is difficult for the filter to deal with both the waste products generate by the sturgeon and the breakdown of large amounts of leftover food. To avoid fouling the aquarium, leftover food must be removed approximately fifteen minutes after the sturgeon are fed. The easiest way to do this is to use a scoop net to strain the leftover food from the tank. This is why it is important to not have any gravel in the aquarium.

•As the sturgeon grow they will need more food. Watch the amount left over after each feeding. If there is a lot, reduce the size of the feeding. If there is almost none, increase the size of the feeding. Watch and make sure that all of the sturgeon get something to eat. Typically some of the fish will start to grow faster. If there is not enough food, they will get almost all of it and the smaller sturgeon may start to starve.

Salt Baths

•While they were in the hatchery, the sturgeon were given a salt bath every week. Salt bathes are usually given to treat gill fungus. If the fungus develops to the point where it is visible on a young sturgeon, it is usually too late for treatment and the sturgeon will die.

• Sturgeon in aquariums should also be given a salt bath every week for at least the first four weeks. After that time the frequency of salt baths may be reduced.

•To give a salt bath, put four litres of aquarium water into a container such as an ice cream pail. Add two level tablespoons of uniodized salt to the four litres of water and stir to dissolve. Our schools use only salt supplied by Natural Resources. Gently move all of the sturgeon from the aquarium into the salt bath. Leave them there for a maximum of five minutes. Watch them carefully all of the time that they are in the salt bath since it can be stressful. The sturgeon may become quite agitated when they are added to the salt water, but they should calm down. If a sturgeon does not calm down, or starts to have problems maintaining its equilibrium, return it to the aquarium immediately.

•After the salt bath, take one cup of salt water and add it to the aquarium. This is a good idea for the health of the sturgeon. The presence of salt ions in the water also helps reduce the toxicity of the nitrites. Nitrites are produced as the waste products excreted by the sturgeon break down. Until the filter is fully established (a process taking about 40 days) nitrite levels can become very high and can even kill the sturgeon. A small amount of salt in the water is important protection against nitrite toxicity.

•Salt baths may be considered a universal panacea for any problem that the sturgeon fingerlings are having. It is almost the only treatment option available for a sick sturgeon. A salt bath may be given to a sick sturgeon at any time (not just once a week). They can even have more than one in a day; however, they should still only stay in the bath for five minutes. It is not entirely clear why a salt baths help. One theory is that it may help maintain ion levels in the sturgeon's blood in the same manner that a saline intravenous injection does for a person who is in shock.

Young Sturgeon

Look carefully at the sturgeon, which you are raising in your aquarium. These fish came a long way for us to learn from them. Few people have the opportunity to see sturgeon when they are this young. The most noticeable feature is the five rows of sharp scutes, which run along the length of each fish. The scutes are hard and sharp and are an important defense against predation. By the second year the scutes will have developed to the point where the sturgeon are as dangerous a bag full of razor blades. It is hard to imagine how even a pike could eat one. As they grow the scutes continue to become larger and stay very sharp. As they mature the scutes will remain, but the sharp projecting hook will disappear. This reduction in the protection the scutes offer no longer matters since the sturgeon are too large for any other fish to eat by this time.

The scutes of a small sturgeon are so sharp that one once seriously damaged an inflatable boat. Fisheries staff were tagging sturgeon early in the spring, shortly after the ice went out. They were pulling their net into their boat and did not feel any sturgeon in the net. A small sturgeon, only about 50 cm long, was pulled over the side of the pontoon cutting a large slash in it. The boat immediately started to collapse and they were lucky to reach the shore before the boat sank.

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