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The animal care technician had a wonderful surprise recently! While caring for our friends in the freshwater aquarium, she found eggs on the predatory side of the tank (see previous posts about how the freshwater tank is divided). Further great news is that there were two separate species of eggs – indicated by two different colours.
As soon as they were discovered, the technician decided to move them to the small-game side of the tank – hoping that this would keep them safe. However, when she returned to check on them, one of the “docile fish” was having himself a delicious snack of caviar! So, the next step was to further isolate the eggs by placing them in a floating basket within the tank. This will keep them safe and in the same climate and environment to which they are accustomed. Now we can only wait and see if/how these eggs develop.
This news is very exciting for the exhibits team. And it’s not simply the excitement that accompanies new babies, but because it means that the climate and ecosystem they have created in that particular tank so closely mimics nature, that the fish’s reproductive cycles have continued on as though they were still in the wild. They are comfortable and secure enough to produce offspring – which gives the team confidence that these fish have adapted very well to their new home!
You may remember this juvenile Largemouth Bass from an earlier post…he had been found on the “small game” side of the freshwater aquarium, eating the bait fish (in this case an Emerald Shiner).
You see, in order to demonstrate a more comprehensive ecosystem and food chain, we wanted to show both large game and small game fish in the same tank. However, this poses a problem in that the big guys will eat (as seen before) all of the little guys. The solution is an amazing design; the aquarium is discreetly bisected, dividing it into two separate sections.
This small bass had found a bit of an “overpass”- a very narrow gap at the top of the rock wall – where it was possible to shimmy and wiggle his way onto the other side (very sneaky!). This would have taken fortitude, spirit…guts! It would have been a perilous, risky endeavor. And it paid off…he was KING on the small game side of the tank, not to mention having all the food he could eat!
Imagine his defeated disappointment when he was captured and put back on the large game side. Now he’s just a small fish in a big pond tank again.
Since the upcoming water gallery has 3 aquaria featuring live creatures, you might be wondering where they all come from! For the freshwater aquarium, staff members go out on fishing expeditions right here in Ottawa. Most recently they went to Petrie Island in the East end of the city, and brought home a good haul of fish like Black Crappies and Perch. When staff members go out fishing, they only use nets as a means to catch the fish since fishing poles and hooks can cause damage. In fact, some of the fish that were caught had hook damage already. These fish will have to be observed to see if they heal in their new home, and if they don’t they likely won’t go on display in the gallery.
A drip tube connects the quarantine tank to the newly caught fish.
After the fish are caught, they are brought back to the museum to begin the acclimatization process. Out in the Ottawa River, the fish are used to temperatures around 4 or 5 degrees, but the freshwater aquarium at the museum is kept closer to 15 degrees, meaning the fish have to adapt slowly so they don’t get too stressed out. In order to help them adapt, the cooler where the fish are kept right after they are caught is set up next to an aquarium where a drip tube connects the two. The drip tube contains warmer water and oxygen, and after a few hours the fish were looking much healthier than when they were caught! Another trick to help the fish adapt is to leave the light off in the room where they are being kept; bright lights could be stressful!
Newly caught fish being moved into quarantine tank
The fish have now been moved into a quarantine tank where they will stay for a few weeks and receive treatments to ensure they aren’t sick or carrying any harmful bacteria. Once staff is sure they are healthy and won’t harm the other fish in the tank, they will be moved into the freshwater aquarium in the gallery! Although it takes a while to make sure the fish are healthy and will survive in the museum environment, all of the fish on display in the freshwater aquarium are examples of our local biodiversity, and not purchased from a store or supplier.
Largemouth Bass eating Emerald Shiner
So, you can imagine that a person can grow fond of these little swimmers. Well, this morning, upon visiting my buddies, I discovered that one of the largemouth bass had swallowed an Emerald Shiner WHOLE. What a pig! I mean, the meal was barely smaller than the consumer!
And so, not possessing a gullet large enough to swallow such large prey, and not having the common sense to spit it back out…the bass just swam around for the rest of the day with a big tail sticking out of it’s mouth. Seriously bad table manners!
After hours spent like this I started to worry for pig-fish’s safety. I mean, how long can one survive with a decaying fish stuck in the throat? And will that rotting corpse in the bass’ mouth cause devastation to the rest of the fish living in the aquarium? But my concern has been assuaged--because Stacey (CMN Exhibition Technician extraordinaire) assures me that this is quite common. Pig fish the bass will swim around, allowing the shiner to decompose, for as long as it takes. And everyone will be fine. Well, not the Emerald Shiner…he is a goner.
Now that a variety of fish are calling the fresh water tank home, the next step is working out the feeding procedures to suit all the different breeds. With the aquarium being divided into two sides, one side containing larger game fish and the other side containing smaller bait fish, the diet requirements of the different fish need to be considered. At the moment, all of the fish get fed every two to three days and all of them enjoy smaller fish for their meals! The bait fish can also eat worms, larva and a variety of other small specimens. In the future, staff plan to introduce breeds like Sun Fish, Rock Bass and Large and Small mouth Bass to go along with the Pike and Black Crappie that live on the game fish side, and Lager Birch, Creek Chubs and small minnow-type fish to live on the bait fish side of the aquarium. The process of introducing these new specimens, as well as determining their feeding requirements is slow, and involves a learning curve for staff who have to monitor how the fish adapt and the behaviours they begin to exhibit in their new environment. Some of the fish previously lived in smaller aquaria so it’s expected that in the new larger tank, where there is more territory to defend, the fish may behave differently than before. The logistics of how the feeding will be done once the exhibit opens depends on factors like how all the specimens get along, the number of fish in the tank as well as the temperature of the water. Did you know that the cooler the temperature of the water, the less the fish will eat? There is a lot to consider when establishing and maintaining an aquarium like this which includes such a large variety of specimens, but so far everything is on track, and the freshwater aquarium will certainly be an exhibit highlight come the grand reopening in May!
Black Crappie enjoys a Goldfish for lunch
There are fish in the Fresh Water aquarium! A few Emerald Shiners have been introduced to the aquarium as part of the process of establishing the biological system, and the fish are doing their jobs well! Immediately after the fish were introduced, ammonia levels in the aquarium spiked a bit which was expected, since fish naturally excrete ammonia. However, since then ammonia levels have been dropping which means there is some successful biological activity in the tank that is naturally starting to deal with the ammonia. No supplements have been added in close to a week which also confirms that the fish are doing their jobs! Staff will continue to introduce Shiners to the tank until the biological system has been fully established and it is safe to introduce the permanent specimens to the aquarium, which will include clams, mollusks and bass.
Emerald Shiners in Fresh Water Aquarium
I assumed the process of changing the water in this giant aquarium would be complicated; however after witnessing a water change today I realize it is actually very efficient and well thought out. Everything is done from the mechanical room and involves turning a few knobs to open and close some shut off valves. Of course the process is closely monitored to make sure the proper amount of water comes in and out as well as making sure the water is the correct temperature, but the manual labour involved in changing the water is minimal. The new water that is brought into the tank is just tap water from the city which is very cold and could therefore change the temperature of the aquarium by 2 or 3 degrees, which is stressful on the fish, but also helps level out ammonia. Monitoring the temperature is important, but again is largely managed by the machines that support the aquarium. Overall, the process of changing the aquarium water is beneficial not only to museum staff but also to visitors because once the exhibit opens it means their visits won’t be interrupted by maintenance work. Visitors won’t even be able to tell when the water is being changed even when it’s happening right before their eyes!
In order to establish a healthy biological environment which will naturally control ammonia levels, staff has used a biological supplement in the aquarium to speed the process up a bit. The supplement provides powerful, beneficial bacteria that will allow for the growth of flora which will metabolize high amounts of ammonia and nitrites (another harmful chemical for fish!) in the aquarium. Usually it takes 6-8 weeks for an aquarium to establish a biological system on its own, however staff is attempting to speed the process up so the aquarium will be thriving, lots of things will be growing and the fish will be used to their new home by the time the exhibit opens in May. After introducing the supplement to the aquarium, staff tested the levels the following day and discovered the ammonia levels had been reduced by half! They also found that nitrite levels were nearly zero which is excellent news for the fish. Staff will continue to test the water to maintain healthy levels and if all continues to go well more fish will be introduced to the tank soon!
Testing ammonia levels
An important step in setting up the fresh water aquarium, where plants and fish will thrive is making sure the water chemistry is healthy and can support the specimens living there. After initially filling the tank and introducing a few fish as part of the seeding process, staff found that the levels of ammonia in the water had spiked since fish release ammonia through their gills, waste and urine. In an aquarium that has an established biological system ammonia is naturally fought off without threat to the fish, but part of the challenge in developing a healthy aquarium environment is controlling these levels so all the new fish and plants coming in will be healthy!
If you were wondering about the “Do Not Clean” sign on the side of the aquarium, it isn’t because the museum is opposed to cleanliness, but to prevent a potential well meaning cleaner from coming along and using a product like Windex which contains ammonia, and could damage the aquarium!
Staff member extracts water for testing
Setting up an aquarium in a museum is not as straightforward as you might think, especially one that holds 1000 pounds of water! There are mechanical, chemical and biological factors to consider when installing a successful and thriving tank. This particular aquarium will eventually hold a variety of species including both predators and prey. How is it possible that both predators and prey can survive in the same aquarium for longer than a few minutes? Well the tank is actually divided down the middle by a sheet of clear Plexiglas, which is imperceptible even when standing right next to it. One side will feature smaller fish which would usually be food for the bigger fish that will live on the opposite side of the tank. This will allow museum visitors to see both kinds of fish together, but saves staff the trouble of having to constantly replace the smaller fish!
Partially cleaned Aquarium
The division in the aquarium is noticeable in the photo above, because the left side has been cleaned recently, and the right side has not! The aquarium is looking much cleaner than last week, and this is because staff has been spending a few hours everyday cleaning the filters, scrubbing the sculpture inside the tank and moving the rocks around to get rid of all the dirt and grime that has accumulated. These are all things that need to be done to begin the process of creating an environment where fish can survive. Another important step is something called “seeding” which involves introducing a few small fish to the tank so they can start to contribute their fish-like qualities (like their feces!) to the environment. Fish feces contain digestive enzymes which help establish a successful biological system in the aquarium, or any environment they inhabit. Does this make you think twice about going for a swim in a big fresh water lake?
Mechanical set up for Fresh Water Aquarium
Of course, not everything found in the aquarium is useful. There is a large mechanical component to maintaining the aquarium, which is kept in a separate room in the back corner of the exhibit. This is necessary because once construction is completed the top and bottom of the aquarium will be enclosed and surrounded by information panels, limiting access to the aquarium. The white tube in the tank which is semi visible near the top (but will be completely disguised eventually) is a surface skimming tube that is hooked up to the plumbing and sends the debris it collects to the filtration system in the back room. After the initial installation of the aquarium, as well as filtering out chemicals, dust and dirt, staff members were even finding big chunks of plastic in the filters! It will be about 3-6 months before the tank and the mechanical systems will be running smoothly and relatively by themselves, requiring less work from staff, and minimal maintenance. Once the exhibit is done and the cleaning and filtration systems are functioning to their full abilities, the water in the tanks will only need to be changed at a rate of 10% a week. This is what is expected, but of course a certain amount of trial and error is involved, so it’s hard to say for certain how things will be run in the future. Hopefully according to plan!
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