Shell dwellers
Encyclopedia
The terms shell dwellers or shelldwellers, shell-breeding, or ostracophil are descriptive terms for cichlid
fish
that use the empty shells of aquatic snails as sites for breeding and shelter. The terms have no taxonomic basis, although most shell-dwelling cichlids are from Lake Tanganyika
s lamprologine lineage. Many shell dwelling cichlids are popular with fishkeepings and are frequently kept in aquaria
.
the shells inhabited are from the genus Neothauma
, while shells used by Pseudotropheus lanisticola in Lake Malawi
are from genus Lanistes
.
. Most, however, are not obligate shell-breeding cichlids and will spawn in other caves or crevices.
, along the coasts of Zambia
, Democratic Republic of Congo, Burundi
and Tanzania
.
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.
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, dependent 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.
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.
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
that use the empty shells of aquatic snails as sites for breeding and shelter. The terms have no taxonomic basis, although most shell-dwelling cichlids are from Lake Tanganyika
Lake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
s lamprologine lineage. Many shell dwelling cichlids are popular with fishkeepings and are frequently kept in aquaria
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
.
Shell origins
In Lake TanganyikaLake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
the shells inhabited are from the genus Neothauma
Neothauma
Neothauma tanganyicense is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Viviparidae.This is the only species in the genus Neothauma.- Distribution :...
, while shells used by Pseudotropheus lanisticola in Lake Malawi
Lake Malawi
Lake Malawi , is an African Great Lake and the southernmost lake in the Great Rift Valley system of East Africa. This lake, the third largest in Africa and the eighth largest lake in the world, is located between Malawi, Mozambique, and Tanzania...
are from genus Lanistes
Lanistes
Lanistes is a genus of freshwater snails which have a gill and an operculum, aquatic gastropod mollusks in the family Ampullariidae, the apple snails.- Distribution :The distribution of the genus Lanistes includes Africa and Madagascar....
.
Shell-dwelling cichlids
Around 24 species of lamprologine cichlids use abandoned shells for shelter and breeding in Lake TanganyikaLake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
. Most, however, are not obligate shell-breeding cichlids and will spawn in other caves or crevices.
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 multifasciatusNeolamprologus multifasciatusNeolamprologus multifasciatus is one of the small shell-dwelling cichlids endemic to Lake Tanganyika. The male reaches five centimeters in length, and the female only 2.5 cm. This makes them one of the smallest cichlid species in the world. Its natural habitat is the neothauma shell beds of...
, Neolamprologus similisNeolamprologus similisNeolamprologus similis is a shell-dwelling cichlid native to Lake Tanganyika in east Africa. N. similis is copper coloured with vertical white stripes running from the head to near the base of the tail. It typically grows to between four and six centimeters in size...
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 ocellatusLamprologus ocellatusLamprologus ocellatus is a type of shell dweller from Lake Tanganyika. It is a popular aquarium fish due to its small size, appearance, and intelligence. Lamprologus ocellatus are members of the cichlid family....
, Lamprologus stappersi, Lamprologus speciosus, and several species much more rare to the hobby. - The LepidiolamprologusLepidiolamprologusLepidiolamprologus is a small genus of cichlids endemic to Lake Tanganyika in eastern Africa. It is closely related to Altolamprologus....
group, now considered NeolamprologusNeolamprologusNeolamprologus is a genus of cichlid fishes endemic to eastern Africa with all but one species occurring in Lake Tanganyika. It is the largest genus of cichlids in Lake Tanganyika and also the largest genus in the tribe Lamprologini, which includes Altolamprologus, Chalinochromis, Julidochromis, ...
species. These are larger shell dwellers and some may prefer mud-dwelling in the wild. They include Neolamprologus boulengeriNeolamprologus boulengeriNeolamprologus boulengeri is a species of fish in the Cichlidae family. It is endemic to the northern part of Lake Tanganyika, where is found in the waters of Burundi and Tanzania....
, Neolamprologus hecquiNeolamprologus hecquiNeolamprologus hecqui is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika, where it is found in the waters of Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia....
, Neolamprologus variostigma and Neolamprologus meeliNeolamprologus meeliNeolamprologus meeli is a cichlid species in the subfamily Pseudocrenilabrinae. It is endemic to Lake Tanganyika, where it is found in the waters of Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia....
. - The AltolamprologusAltolamprologusAltolamprologus is a small genus of pseudocrenilabrine cichlids endemic to Lake Tanganyika in eastern Africa. They inhabit areas of the lake with large amounts of rock, most frequently in water two to ten metres in depth. Two formally described species comprise this genus, with perhaps one dwarf A....
varieties include Altolamprologus compressicepsAltolamprologus compressicepsAltolamprologus compressiceps is a species of fish in the Cichlidae family. It is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. Its natural habitat is freshwater lakes. It is not considered threatened by the IUCN....
"Sumbu" and other locational varieties that remain smaller than the normal A. compressiceps in order to use shells. - The TelmatochromisTelmatochromisTelmatochromis is a small cichlid genus of the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to Lake Tanganyika in East Africa.-Systematics:7 species are included here...
genus contains one definite shell dweller, TelmatochromisTelmatochromisTelmatochromis is a small cichlid genus of the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to Lake Tanganyika in East Africa.-Systematics:7 species are included here...
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 brevisNeolamprologus brevisNeolamprologus brevis is a small shell-dwelling cichlid endemic to Lake Tanganyika. The male reaches 5.5 centimeters in length, and the female is a bit smaller. N. brevis is unusual among shell-dwelling cichlids in that both fish in a pair share the same shell...
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 mbunaMbunaMbuna is the common name for a large group of African cichlids from Lake Malawi. The name mbuna means "rockfish" in the language of the Tonga people of Malawi...
in Lake MalawiLake MalawiLake Malawi , is an African Great Lake and the southernmost lake in the Great Rift Valley system of East Africa. This lake, the third largest in Africa and the eighth largest lake in the world, is located between Malawi, Mozambique, and Tanzania...
at a bare 7 cm.
Range
Shell dwellers are found throughout Lake TanganyikaLake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
, along the coasts of Zambia
Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....
, Democratic Republic of Congo, Burundi
Burundi
Burundi , officially the Republic of Burundi , is a landlocked country in the Great Lakes region of Eastern Africa bordered by Rwanda to the north, Tanzania to the east and south, and the Democratic Republic of the Congo to the west. Its capital is Bujumbura...
and Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
.
Diet
Shell dwellers are carnivores that promarily feed on zooplanktonZooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
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.
Reproduction
As with other cichlids they protect their young, and the distinctive shell-dwelling provides them with a defensible nursery.Generally eggs
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
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, dependent primarily on temperature, and the yolk sac
Yolk sac
The yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
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 mbunaMbuna
Mbuna is the common name for a large group of African cichlids from Lake Malawi. The name mbuna means "rockfish" in the language of the Tonga people of Malawi...
in that lake, but the Tanganyikan shell dwellers were found primarily in the late 1970s and early 1980s. Altolamprologus compressiceps
Altolamprologus compressiceps
Altolamprologus compressiceps is a species of fish in the Cichlidae family. It is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. Its natural habitat is freshwater lakes. It is not considered threatened by the IUCN....
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
Neothauma
Neothauma tanganyicense is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusc in the family Viviparidae.This is the only species in the genus Neothauma.- Distribution :...
shells, ocean turbo shells, escargot shells, whale eye shells, and Ampullariidae
Ampullariidae
Ampullariidae, common name the apple snails, is a family of large freshwater snails, aquatic gastropod mollusks with a gill and an operculum...
-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.