This posting will give you a glimpse into what it takes to successfully maintain the thriving community of animals that call the Academy’s 110,000 gallon Amazon Flooded Forest display home. Our tank, located at the bottom of the Academy’s rainforest dome, is teeming with hundreds of fishes–pacu, cichlids, leporinus, silver dollars, a giant river turtle, a tarpon, peacock bass and four species of catfish. Most significntly we also display three arapaima, one of the largest species of freshwater fish in the world, two of whom exceed 8 feet in length!
Fish kept in an aquarium are confined to a very small quantity of water as compared to their natural habitats in the wild. In the wild, fish wastes are instantly diluted. But in an aquarium, waste products can quickly accumulate to toxic levels. These waste products include poop, scraps of uneaten food and plant material. The latter is an especially large factor for a tank sitting at the bottom of a rainforest! Skimmer baskets located in three different spots collect most of the leaves that fall into the water and are cleaned every week by aquarium Biologists.
If left to accumulate this organic material would eventually decay, releasing ammonia. Even small amounts of ammonia are deadly for fish. Fortunately, the world is full of bacteria that want nothing more than to consume the ammonia and convert it into less toxic substances (nitrite then nitrate). All the bacteria require to perform this beneficial function is a surface to attach to and oxygen rich water. For our display we filter our water through three large sand filters (see photo below).
The sand removes any fine particulate matter and provides lots of surface area for bacteria to colonize. Remember that nitrate is only less toxic than ammonia, not non-toxic. Over time the nitrates would accumulate until they, too, became toxic. Also, because nitrate is a fertilizer, high nitrate levels can lead to excess algae growth. Part of our routine maintenance is to “back-wash” our sand filters twice weekly. Our engineers flush 20,000 gallons of water backwards through the sand and into the Academy’s water recycling system. This physically removes any debris from the filters and, when the tank is refilled with fresh water, decreases our nitrate levels by 20% each time.
Like a living organism, the life of our Amazon display depends on its circulation, which is the flow of water through its filters and around the tank. In our system the movement of water through our filters exposes a constantly changing air/water surface interface through which the major exchange of gasses, primarily water and carbon dioxide, takes place. The pumps we use, shown below, are powerful enough to completely turn over the 110,000 gallons in our tank once every hour!
For all the inhabitants of the Flooded Forest here at the Academy it is, fundamentally, the invisible water conditions that make their display a home away from home!