Shelldwellers: Tiny Tanganyikan Treasures

Neolamprologus multifasciatus © Clint Norwood

The shelldwelling fish of Lake Tanganyika in East Africa, known variously as shelldwellers, shell-dwellers, shell dwellers, and the familiar “shellies,” are often kept for their size but are perhaps most notable for their evolutionary position. Tanganyika is one of the oldest lakes in the world, often estimated at around 12 million years old. Unlike the more recently formed lakes Malawi and Victoria, the cichlid of Lake Tang have had plenty of time to adapt into a variety of niches. Because of the high mineral content of the lake, the abandoned shells of dead snails stay whole and are not dissolved by the water. The combination of these two factors led to the development of shelldwelling cichlids which use the shells, rather than the lake’s many caves, as protection and for reproduction.

Although one species of shelldweller (Neolamprologus callipterus) occasionally contains males which can grow to nearly a foot in length, the most famed characteristic of shelldwellers is their small size. The most popular species barely top 2”, and variants are being discovered which never reach half that. For the African lover with little free space or the relative newcomer not willing to dive into a 6’ tank, shellies provide maximum intelligence in minimal space. A ten gallon tank suffices for a few species, most notably Neolamprologus brevis and Neolamprologus multifasciatus, and scaling up to a 20—still tiny by rift lake standards—allows for a fair colony or a variety of other species choices. Indeed, nearly every known species of shelldweller can be safely housed in a 20 gallon long.

In the wild shelldwellers are micropredators and opportunists, but in the aquarium even wild-caught fish soon learn that pellets make tasty, much more filling prey. As smart as their larger cousins, a routine will allow a shellie to learn within days that the movement of a hand towards the food canister, or the opening of a lid, is a signal to congregate at the front and wait for food. However, even among those fish which understand mealtimes it remains quite common to see them grab at some speck in the water and test it for palatability. A good cichlid pellet is the safest bet, but remember it will need to be quite small to be easily eaten by these diminutive fish. This can be rounded out with frozen, live, and freeze-dried foods, but shellies are unlikely to appreciate significant vegetable matter in their diets. Also, be advised that while over time they may learn to come to the surface and eat, shellies are bottom dwellers, and sinking foods will be appreciated.

Housing shelldwellers can be as simple or as complex as one makes it. A ten gallon with two pairs of N. brevis, which has adapted to deal with the sparse shells in its regions by sharing a shell with its mate, may have nothing more in terns of decorations than a few shells, a nice layer of sand, and perhaps a rock to mark the territorial boundary. However, the same tank done up for a colony of N. multifasciatus might have a layer or slate, a bit of sand, and as many as a few dozen shells, replicating the deep shell beds of their natural habitats. Beyond sand and shells, the shellie tank may have rocks, though not enough to impinge on floor space, plants, even castles and bubbling divers. As long as the shellies have what they need (floor space, sand for most species, shells to live in), the design is up to the owner.

When selecting shells, it helps to think of the behaviors of the fish. Choosing shells with round openings is important, as the shellies, spooked and dashing into the shell, may get caught in an oddly-shaped or tightly wound example. Marine turbo shells are the correct shape and often the ideal size but are quite heavy and difficult for shelldwellers to move. Escargot shells are more difficult to track down outside of urban areas but are the right shape and quite light. Discarded apple and mystery snail shells can be perfect but may not be available in quantity. The alternate options, including PVC elbows and upside-down terracotta pots, will allow for breeding but eliminate any opportunity to observe the real behaviors and complex natural behaviors of the fish and their shells. Of course, authentic Neothauma shells, while somewhat pricey and often difficult to track down, are the perfect shells for any shelldweller tank.

While an article of this length could hardly begin to cover the complexity and joy of the shellie hobby, it should create a basis for further research and, perhaps, the impetus to get involved with these beautiful, personable fish.

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