Shell Dweller Fish
wikipedia
Shell Dwellers are a group of cichlids from Lake Tanganyika with
one definite example from Lake Malawi. The shell-dwelling species
are marked out by their choice of shelter and breeding caves.
Because Lake Tanganyika has very hard, alkaline water, the empty
shells of long-deceased snails of the genus Neothauma do not
dissolve, and have built up over millions of years to litter the
lake floor.
Over time about 20 of the lake's many cichlid species have
adapted to use these abandoned shells for safety and breeding.
The species are some of the smallest in the cichlid world, some
as small as ca. 3 cm, although males of one species,
Neolamprologus callipterus, can reach ten times that size.
The fish are varied in shape from the laterally compressed, as
with a variety of Altolamprologus compressiceps that has become
small and shell-dwelling, to the elongated, as with
shell-dwelling varieties of Telmatochromis. Most species fall
between those two extremes, as with the species currently
assigned to the Lamprologus and Neolamprologus genera which
shell-dwell.
Shell dwellers are of little interest beyond the aquarium hobby,
but within it they are valued for their intelligence and compact
size.
Types of Shell Dwellers
There are several groups the shell dwellers can be placed into:
Colonial shell dwellers. Quite popular for their familial
behavior, these fish are native to or, in some cases, create
their own shellbeds, with piles of dense shells. Species include
Neolamprologus multifasciatus, Neolamprologus similis and
Neolamprologus callipterus
The ocellatus group has the most attractively patterned and many
of the most aggressive of the shell-dwelling species, which share
a similar body shape and territorial behavior. It has been said
that if sharks behaved as this group does, the world's beaches
would be abandoned. Species include Lamprologus ocellatus,
Lamprologus stappersi, Lamprologus speciosus, and several species
much more rare to the hobby.
The Lepidiolamprologus group, now considered Neolamprologus
species. These are larger shell dwellers and some may prefer
mud-dwelling in the wild. They include Neolamprologus boulengeri,
Neolamprologus hecqui and Neolamprologus meeli.
The Altolamprologus varieties include Altolamprologus
compressiceps "Sumbu" and other locational varieties that remain
smaller than the normal A. compressiceps in order to use shells.
The Telmatochromis genus contains one definite shell dweller,
Telmatochromis sp "temporalis shell," and many species that will
shell-dwell in captivity.
The brevis group contains a number of species with heavy bodies
and gentle temperaments, including Neolamprologus brevis and
Neolamprologus calliurus.
The signatus group contains slim, reflective species, including
Neolamprologus signatus, Neolamprologus ornatippinnis and
Neolamprologus kungweensis.
The Malawi shell dwellers, which may comprise several species but
as yet only Pseudotropheus lanisticola is certain, one of the
smallest mbuna in Lake Malawi at a bare 7 cm.
Range of Shell Dwellers
Shell dwellers are found throughout Lake Tanganyika, along the
coasts of Zambia, Democratic Republic of Congo, Burundi and
Tanzania.
Shell Dweller Fish
Feeding Shell Dwellers
Shell dwellers are carnivores that primarily feed on zooplankton
and other microscopic and near-microscopic foods.
Cichlids' distinctive pharyngeal teeth, in the
throat of the
fish, are present in shell dwellers, though small. Armed with
those and the usual teeth along with the typical dissolving
qualities of water shell dwellers can eat a variety of foods in
the wild and in captivity. Many species have been known to pull
small snails from their shells to eat, to catch and devour the
fry of other fish, and to go after small crustaceans.
Breeding Shell Dwellers
As with other cichlids they protect their young, and the
distinctive shell-dwelling provides them with a defensible
nursery.
Generally eggs are laid by the female within the shell and
fertilized as she lays them or immediately after by the male.
The female will protect the shell, fanning her pectoral fins to
keep the internal water oxygenated, and often rearranging the
substrate to create barriers or to hide the shell from predators.
Eggs hatch within 48 hours, dependant primarily on temperature,
and the yolk sac is absorbed within five days. Fry typically
emerge from the shell a week after spawning, although they remain
quite benthic for days or weeks after their emergence.
Shell dwellers as aquarium fish
The Malawi shell dweller, Pseudotropheus lanisticola, was first
identified in 1964 along with many other mbuna in that lake, but
the Tanganyikan shell dwellers were found primarily in the late
1970s and early 1980s. Altolamprologus compressiceps was
identified in 1958 but the shell-dwelling varieties were found
much later.
The shell-dwelling species' needs are very similar. The basic
aquarium setup and equipment are appropriate with a few changes.
First, the substrate should be sand. Many of the species are very
accomplished diggers and for security may bury all or part of a
shell, use sand as a territorial barrier, or generally amuse the
owner by spitting, sifting, or throwing it. Second, hard,
alkaline water must be provided, which should also be kept free
of ammonia and nitrites and with low nitrates. Finally,
appropriate shells must be provided. Common shells used for shell
dwellers include authentic Neothauma shells, ocean turbo shells,
escargot shells, whale eye shells, and Ampullariidae-family
shells. Shells must be of an appropriate size for the species,
have a round opening, and have open coils. Numbers of shells will
vary; for colonial species, hundreds may be ideal. For brevis
types, a single shell per pair is often representative.
