The Tennessee Aquarium: A Must-See for Native Fish Enthusiasts

After the talks, we gathered across the street for a group photo in front of the Tennessee Aquarium's main exhibit building. Then we filed inside to see many of the fishes we had heard about earlier.

Most public aquariums in the U.S. have only a cursory display of local freshwater species. The Tennessee Aquarium is almost wholly devoted to them! Sitting on the banks of the Tennessee River, this $45 million facility, which opened in May 1992, bills itself as the largest freshwater aquarium in the world. Focusing primarily on the Tennessee River and related systems, the Aquarium's exhibits are organized to guide visitors on a journey from the river's source in the Appalachian high country, through its midstream, and finally, to the Mississippi Delta. In addition, the Aquarium boasts impressive freshwater displays with fishes and other aquatic animals from other rivers in the world. There's the Volga River in Russia, with its beluga sturgeon and huchen trout; three tanks on the Amazon, one with tetras and discus, one with red-bellied piranha, and a large flooded forest tank with arapaima, arowana, pacu, and red-tailed cats; a tropical Asian exhibit with some of the most colorful barbs you'll ever see; a tank featuring the colorful rainbowfishes of the Fly River in New Guinea; an exhibit featuring the endangered freshwater fishes of Madagascar; and two exhibits portraying the Zaire River, including a massive exhibit featuring tilapia, distichodus, river puffers, and the comically thick-lipped bubu catfish (Auchenoglanis occidentalis). But it's the native displays we were oohing and aahing over. They certainly put the best efforts of basement fishkeepers like myself to shame.

Most of the Aquarium's exhibits are true "biotope" displays, combining animals from different taxa, lush plant growth, and naturalistic lighting to portray ecosystems, not just "fish in boxes." This is immediately evident in the first stop on our tour, the Appalachian Cove Forest located on the Aquarium's top (4th & 5th) floors. Termed an "immersion" exhibit because visitors walk through it, the Cove Forest re-creates the mountain source of the Tennessee River, complete with moss-covered rocks, indigenous plants (rhododendrons, azaleas, wildflowers), deciduous trees, free-roaming bullfrogs and birds, logs fallen across streams, waterfalls, and the constant roar of rushing water. A unique feature of this exhibit is that it changes with the seasons; the greenhouse-like roof opens up, making it hot in the summer, cold in the winter, and full of falling leaves in the autumn. At one end of the forest you can watch two male river otters (the only mammals on display at the Aquarium) frolic in a stream. Once nearly extinct in Tennessee, the river otter has staged a comeback in the wild, thanks to release programs begun in the 1980s. At the other end of the forest nearly 50 brook, brown and rainbow trout (all hatchery raised) swim in a pool, their muscular bodies poised in constant anticipation of their next meal. Two other tanks showcase a wide variety of dace, shiners, darters, and other smaller mountain stream fishes, including the endangered spotfin chub. Scattered throughout the exhibit are several snakes (timber rattlers, copperhead, black rat, corn, king, and northern pine), safely ensconced in exhibits built into the trunks of artificial trees. Some 24 species of year-round and migratory birds fly freely overhead.

You exit the Cove through a set of revolving doors, leaving the warm, moist air of the forest (this was in June, after all) for the dryer, air-conditioned air of the Aquarium's main exhibit galleries. First up is an 18-foot deep, 30,000- gallon re-creation of a mountain sink, the geological formation that occurs when the force of a waterfall wears a deep ravine into the waterbed. It takes a second, but you realize you're looking underneath the waterfall you saw in the forest. This is truly an impressive sight, as over 150 trout are at play under the churning waterfall. (Not surprisingly, the dissolved oxygen here is usually at 100%.) This water eventually spills over into a fast-moving mountain stream in which brook trout and white suckers hide behind boulders and beneath undercuts in the banks, fighting against the current. (The presence of young-of-the-year rainbow trout shows that fish are reproducing in this exhibit.) The entire system is naturally lit (be sure to visit it at mid-day to see the fishes in all their splendor). All told, the Cove Forest and its connecting streams display 34 species of fish (Table 1).

Table 1. Fishes in the Tennessee Aquarium's Appalachian Cove Forest Exhibits

(1) Endangered species propagated at Conservation Fisheries, Inc. and raised at the Aquarium.
(2) Exotic species introduced into Tennessee. A hybrid brown x rainbow trout also is on display.

After the trout streams you take a detour through a temporary exhibit, the eerily beautiful "Jellies: Phantoms of the Deep." Jellyfishes require different types of aquaria called "kreisels." These specially built tanks circulate the water in a calm but constant way, preventing the water-filled creatures from being sucked up intake tubes or smashed against the aquarium acrylic. If you've ever seen a Lava lamp in a darkened room, then you'll have some idea of what it's like to watch shimmering jellies gracefully "swim" in their brilliantly illuminated tanks.

After the jellies you enter another immersion exhibit under a glass roof, "Delta Country," depicting the sultry areas where the Mississippi River slows to meet the sea, joining creeks, streams and lakes to form the fertile cypress swamps of the Louisiana Bayou. This exhibit is divided into four pools where fishes, birds, reptiles and bullfrogs live together (but not always peacefully) amidst a tangle of tree-trunks, vines and hanging moss. The largest of the pools is home to five alligator snapping turtles (including one male that weighs almost 150 pounds, making him more than a century old!), two Florida softshells, three river cooters, a Florida cooter, and a male American alligator that's over 6-feet long. Over a thousand mosquitofish live in this pool as well, providing a constantly reproducing food source for the ever-hungry turtles. Another pool, known by Aquarium staffers as the "snake pit," is a paludarium-like exhibit with burrows built up against the glass, providing close-up views of canebrake and eastern diamondback rattlesnakes. Many diminutive fishes swim in the water portion of this exhibit, including banded pygmy sunfish, but I was hard-pressed to find any. (A complete list of Delta Country's fishes is given in Table 2.) As in the Cove, birds (including a little-blue heron) roam freely. (During a subsequent after-hours visit, I was amused to see wood ducks wobbling down the hallway like nobody's business; they like to leave the exhibits at night and need to be collected the following morning.)

Table 2. Fishes in the Tennessee Aquarium's Delta Country Exhibit

On your way to Delta Country you catch glimpses of the 88,000-gallon Gulf of Mexico tank, the only permanent saltwater exhibit at the Aquarium. You can see it in all its glory standing at the lower of its two stories. Because it's saltwater, with public aquarium staples like sharks, rays and tarpon prowling its depths, the Gulf of Mexico is the most generic of the Tennessee Aquarium's tanks. It's the kind of big, flashy tank the general (i.e., non-native fish enthusiast) public ogles over most. It houses twenty-five species of fishes (Table 3), none of which have been added since the Aquarium opened; in fact, the sting-rays have have given birth to four litters during the past year. (The foot-long babies have been given to other U.S. zoos and aquariums.) Volunteer divers feed the fish daily. The Aquarium hopes to add more fish in the coming year, including moray eels.

Table 3. Fishes in the Tennessee Aquarium's Gulf of Mexico Exhibit

Around the corner from the Gulf of Mexico is the Amazon and other "Rivers of the World." Among them is Canada's St. Lawrence River. This exhibit, which is chilled to 56°F year-round, showcases lake sturgeon (Acipenser fulvescens), lake trout (Salvelinus namaycush), yellow perch (Perca flavescens), walleye (Stizostedion vitreum), and sauger (Stizostedion canadense).

The centerpiece of the Aquarium is its multi-exhibit Tennessee River gallery, featuring fishes and other animals from the Tennessee River and its various nooks and crannies. Graphic displays examine the history of the river, comparing the "original" Tennessee with the river as it now exists as a reservoir system harnessed by 35 dams. (Also included in this gallery is "Turtles: Nature's Living Sculptures--Architecture in Bone," which bills itself as the largest collection of freshwater turtles on public display in the world.) The first tank contains "Miss Patty," the largest largemouth bass (Micropterus salmoides) ever caught during a B.A.S.S.-sanctioned tournament--a hefty 13 lb. 9 oz. She was caught in Corsicana, Texas by Mark Menendez, who donated her to the Aquarium. The second tank re-creates a Tennessee River oxbow; fishes include orangespotted sunfish (Lepomis humilus) and flier (Centrarchus macropterus).

The next Tennessee River gallery tank plunges you into the swamp-like, lily pad-covered waters of northwest Tennessee's famous Reelfoot Lake (featured in the movies In the Heat of the Night and U.S. Marshals). Reelfoot Lake was formed in 1812 as the result of a massive earthquake (perhaps the largest in recorded North American history). The force of the quake caused an 18,000-acre section of cypress swamp to sink 10 feet to form a basin that was covered by water when the Mississippi River's flow was diverted and ran briefly upstream. The exhibit features young paddlefish (Polyodon spathula, front cover), golden shiner (Notemigonus chrysoleucas), blue sucker (Cycleptus elongatus), and a shoal of creek chubsucker (Erimyzon oblongus), among others. The paddlefish enjoy brine shrimp that are dripped in through an air hose from a catwalk above the tank; the instant the shrimp hit the water, the 18 prehistoric filter feeders open their cavernous mouths and strain the shrimp through their long gill rakers. The blue suckers are indeed blue, and sleek; I can see why Scott Mettee thinks they are sexy. They sift through the gravel with great poise and determination. (Note: Neither paddlefish nor blue sucker are currently found in Reelfoot Lake, although they probably once occurred there. The Aquarium is in the process of converting its Reelfoot Lake exhibit into a Mississippi River exhibit.)

Next to Reelfoot Lake are two heavily-planted tanks depicting Tennessee River backwaters. The first one contains starhead topminnow (Fundulus dispar), bluefin killifish (Lucania goodei), bluespotted sunfish (Enneacanthus gloriosus), and banded sunfish (Enneacanthus obesus), among others. The second tank contains the endangered barrens topminnow, sailfin shiner (Notropis hypselopterus), and a number of invertebrates, including spotted royal crayfish (Procambarus pictus), apple snails (Pomacea paludosa), and giant water bugs (Abedus indentatus).

The largest tank at the Tennessee Aquarium is the 145,000-gallon Nickajack Lake exhibit. Nickajack Lake is not a lake; it's the area of the Tennessee River just outside the Aquarium's window. Created by the Tennessee Valley Authority in the 1930s to reduce flooding and to provide drinking water, Nickajack Lake was once shoreline. Its fish inhabit its sunken forests, stump fields, abandoned bridges and road beds. The exhibit, which has a shallow end and a deep (25 feet) end, contains more than 30 species of fishes (Table 4). This is the Tennessee Aquarium display to which I would love to bring a folding chair, a lunch, and park myself in front of for five or six hours. Its enormity, and the size and diversity of its fishes, is breathtaking. Most impressive are the three blue catfish (Ictalurus furcatus) which prowl the tank's deepest water. These 80-pound behemoths are among the largest catfish on exhibit in the U.S. Exotics like common carp and grass carp get equal time, too; when displayed properly, as they are here, their beauty, form and strength overshadow their nuisance status in the wild. In addition to the fishes, two types of divers frequent the tank--the volunteer divers who hand-feed the fishes daily, and the diving ducks, which comically dive-bomb for their food, then bob like corks to the surface.

Table 4. Fishes in the Tennessee Aquarium's Nickajack Lake Exhibit

(1) Exotic species introduced into the United States and found in Tennessee.
(2) Hybrid bluegills (L. cyanellus x macrochirus) also are on display.
(3) Hybrid striped bass (M. saxatilis x chrysops) also are on display.

But our Tennessee Aquarium visit didn't end here. We broke for dinner, then returned for a behind-the-scenes tour led by fish curator Chris Coco and two aquarists, Stephanie Brough and Darlene Walder (NANFA members both). Stephanie maintains the Cove Forest, Reelfoot Lake and backwaters exhibits; she breeds darters, too. Darlene is a fish health specialist who also is responsible for the Aquarium's barrens topminnow breeding program.

I've been on behind-the-scenes public aquarium tours before, and I've always been struck by the constant drone of water pumps, and the labyrinthine network of pipes that snake along seemingly every available inch behind the exhibit walls. The Tennessee Aquarium is no exception. Most of its larger exhibits are filtered two levels down, in a deafeningly loud room beneath the lobby. The main filtration medium is sand. Ozone contact chambers are hidden throughout the building; they help remove dissolved organics from all but the smaller exhibits. Also hidden throughout the building are heat exchangers. Water in copper coils is chilled to 43°F. These coils come in contact with water from the exhibits; how much water is sent through the coils determines how cold the water gets. The trout tanks are chilled to 58°F; they reach 48°F on their own in the winter.

Our tour took us by the Aquarium's life support center; here staffers monitor via computer each tank's water level and temperature 24 hours a day, 365 days a year. If something goes wrong, aquarists and maintenance technicians are on-call to come in and fix the problem and prevent or minimize animal casualties. We also visited the food preparation room and its walk-in refrigerator and freezer. Fishes in the Tennessee Aquarium eat more than 1,200 pounds of restaurant quality seafood each month. ("So does B.G. Granier," someone behind me muttered.)

The most interesting stop on our behind-the-scenes tour was the cafeteria-size quarantine (or "Q") room. Here we saw many recently collected fishes completing their 30-day minimum quarantine, and many fishes that were temporarily off-exhibit. The Q room also is where Stephanie keeps the rack system where she breeds rainbow (Etheostoma caeruleum), blueside (E. jessiae), and Tennessee snubnose (E. simoterum) darters. The rack consists of three separate 5-foot-long hand-built glass tanks with one filtration system (cartridge filter and bio-ball tower). Water is pumped in at one end and goes down stand pipes through gravity into a sump. Water temperature and light cycles are controlled to simulate the change of seasons; water is kept as low as 53°F to simulate winter and up to 72°F to simulate summer.

Access to most of the Aquarium's tanks is from a platform or catwalk above. The spaces here can be pretty cramped with little or no headroom, and aquarists need to be agile to maneuver through them. Aquarists don SCUBA gear and dive into the larger tanks for tank maintenance. For example, in the fall, an aquarist needs to regularly dive into the cold water of the mountain sink to remove tree leaves that are blocking pump intakes. Volunteer divers do much of the hand-feeding in the larger tanks. The Aquarium's volunteer program has over 100 divers.

One of the biggest thrills for a Tennessee Aquarium aquarist is the opportunity to collect fishes from the wild to supplement their exhibits. Aquarists regularly schedule collecting trip and have specially-outfitted trucks with which to bring fishes back. But not all of the Aquarium's fishes are wild-caught. In fish ponds in Cohutta, Georgia, the Aquarium rears sunfishes and sturgeon, and raises larger fishes like catfish and gar to adult size.

After our behind-the-scenes tour we gathered in the suite connected to B.G. Granier's room (aka the "NANFA Room") and discussed everything we had seen and heard that day. We could have sat up all night talking fish, but we needed our rest. Tomorrow we would be hitting the creeks and collecting our own.