Shell Dweller Basics

By LittleMousling
What are Shell Dwellers?
Shelldwellers, or "shellies," are dwarf cichlids from Lake Tanganyika in Africa, one of the well-known rift lakes. This relatively old lake has given its inhabitants 12 million years to specialize, and somewhere along the way groups of rock and cave dwellers began to utilize the additional possibilities of the empty snail shells that litter the lake's floor. The lake, which has extremely high calcium levels, preserves shells more or less for eternity; in some areas there are piles of shells more than ten feet deep. This offers ample opportunity for small cichlids to use the shells as protective caves for themselves and their fry. Because these fish are small, often social, and fairly prolific, they've become popular among those who have the chance to discover they exist!
There is at least one and possibly a couple of shelldwelling Malawi cichlids, considered a subset of the popular rock dwelling mbuna. This younger lake may someday have its own significant variety of shelldwellers; as it stands now, the Malawian P. lanisticola is worth a look.
What water parameters do they need?
Shellies, like other rift lake cichlids, need a high pH, gh, and kh. Hard water with enough buffering capability to maintain a quite basic pH is more or less a must. It is likely that someday a few years or decades from now shelldwellers will be far enough removed from their wild ancestors that they won't need these parameters and will adapt well to most water; however, this is not that day. Shell dwellers will fail to thrive, and certainly fail to breed, if given neutral or acidic water.
Tropical fish, Shell Dwellers should be kept in water of about 76 degrees Fahrenheit, and closer to 80 when breeding. Shellies are very sensitive to high temperatures, most likely because of the lower oxygen levels found in hot water; anything about 85 degrees should be avoided at all costs. There has been some popular experimentation lately keeping a few species, like multis and brevis, at normal room temperatures of 70-72 degrees. They seem to prosper in these temperatures.
What are some common species?
The most common Shell Dweller species are also some of the smallest. The diminutive multi, N. multifasciatus, is a striped Shell Dweller beloved for its colony lifestyle and prolificacy. N. brevis comes in a variety of patterns, from vertical white lines to a brown, unstriped body and a yellow belly spot. One variety, which may turn out to be a separate species, is the smallest known cichlid in the world, usually known as N. brevis "Minuta". L. ocellatus is another species with several varieties, but the most popular type is the "gold" ocellatus, which is bright yellow with a lavender sheen and a pugnacious attitude.
How do I set up a tank for Shell Dwellers?
One of the main reasons shellies are so popular is their small size. Because they have a low bioload and maintain relatively small territories, many fit in surprisingly small tanks.
The basics for keeping a smaller species of shellie include a ten gallon tank, a sand substrate that they can dig in, shells for them to live in, and the traditional accessories like a filter, heater, hood, light, and so on. Plants will not be eaten but may be dug up.
One of the unfortunate aspects of Shell Dweller care is that they need floor space. Therefore, decorative elements like rocks, plastic plants, and plastic castles are best left out of the shellie tank in favor of more shells and sand. This makes shellie tanks fairly flat; luckily the fish themselves are in vivid, engaging 3D!
What kind of shells?
There are lots of shells that make great homes for shelldwellers, starting with the truly natural, Neothauma shells. Shellies in the lake inhabit the empty shells of Neothauma snails of various species. These shells, however, are usually quite expensive and tough to find.
Apple and Mystery snail shells are also fairly natural, if not biotope-accurate. It can be hard to find any good number of large-enough shells, but they're often free and have a good shape.
Hermit crab turbo shells are easily available at pet and craft stores and often cheap. However, they're often too heavy for the fish to move and come in odd colors.
Craft stores sell all sorts of shells, from small conch-shaped shells that work well but look odd to "pearlized turbos" that work well but look odd. These shells can be cheaper, but generally, well, look odd.
Escargot shells are light, big, attractive, and cheap, but a bit harder to find. Upscale groceries, French restaurants, and gourmet shops are the best bets to find these.
For the very convenient but not in any way natural look, small PVC elbows with caps are light and easy to get the fish out of. These are best for fry tanks, but very rarely used for display tanks.
What are some appropriate tankmates for Shell Dwellers?
There are numerous cichlid and non-cichlid tankmates for most shellie species because they're small and relatively gentle. Non-cichlids include the larger livebearers, barbs, loaches, danios, Rainbowfish, and robust topdwelling killifish in a tall tank, even the delicate Tanganyikan killifish can work.
Cichlid options include the schooling Cyprichromis species in larger tanks, numerous rock dwellers (who may predate fry) like Julidochromis, Chalinochromis, Goby cichlids, members of the N. brichardi group, and so on. There are even cases of Frontosa colonies being kept with large and thriving multi colonies; the Fronts keep the numbers down but can't eradicate the prolific shellies.
Shell dwellers, other than P. lanisticola, should not be kept with cichlids from the other rift lakes, riverine Africans, or cichlids from other areas of the world.
Can I breed my Shell Dwellers?
Shelldwellers are some of the easiest Tanganyikans to spawn. Multis are often compared to guppies and convicts in their prolificacy, and most of the other species are similarly inclined. Although they have small spawns (how many eggs, after all, can a 1" fish lay?), they are more than willing to have spawn after spawn after spawn. Patience may be required for the fish to reach maturity; like other Tanganyikans, many species have long growth periods.
    The basic requirements for spawning are:
  • Shells of appropriate size and quantity (more is better for most species but brevis in particular only need a few shells, and will cohabit.
  • Hard, basic, clean water is a must. Numerous small water changes are the best way to go.
  • Tropical temperatures while many species may live quite well in cooler water, higher temperatures are the safe way to go when trying to spawn.
  • Male and female shellies. If you don't know how to sex the species in question, get a group of six and raise them until they pair off.
  • Good food. It doesn't have to be live but frozen, freeze-dried, or high-quality pellet food is better than flake for shellies, who are generally unwilling to go to the surface to eat.
  • Patience!

Can I combine Shell Dwellers?
It's rarely if ever a good idea to have multiple species of shelldwellers in the same tank. There are a handful of possible way it can work. First, in a very large tank, a species can be kept on each end, with a fairly aggressive rock dweller living in a large shell pile between the two to keep them separated. Second, a tank divider, while ugly, will keep the adults apart. Third, a true shellie can be combined with a species that lives in rocks but spawns in shells, like N. caudopunctatus.
The reasons for keeping shellies apart range from aggression to hybridization. Although a small number of shellies interact in the wild (for example, L. ocellatus and N. brevis share territories in Lake Tanganyika) there's a bit of a difference between millions of gallons of lake and even the largest of home aquariums. If that same combination were tried at home, chances are that the more aggressive ocellatus would drive the brevis into the corners of the tank and starve them out. If larger brevis were used with smaller ocellatus to try and even out the aggression, the brevis would probably stress the ocellatus to anorexia. All in all, it's safest to keep shellies apart.

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