Shell Dweller Basics
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
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
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
another species with several varieties, but the most popular type is the
"gold" ocellatus, which is bright yellow with a lavender sheen and a
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
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
larger tanks, numerous rock dwellers (who may predate fry) like
, 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:
Can I combine Shell Dwellers?
- 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
- 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.
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.
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
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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