Multi shell dweller

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: sand.

Behavior

Plant interaction: digs around roots.

Feeding

Micro pellets, crushed flake, frozen baby brine shrimp. Tiny mouths; food needs to be small enough to fit. Will scavenge anything that sinks to the bottom.

Compatibility

• The smallest cichlid commonly kept. A colony in a 40 L tank is one of the most fascinating setups in the hobby
• Need empty snail shells (Neothauma tanganyicense in the wild; escargot shells from the grocery store work fine). Each fish claims a shell and defends it aggressively against neighbors
• Colonies self-regulate; dominant pairs breed, subordinates wait. Population grows steadily and they'll fill whatever space you give them
• Sand substrate is mandatory. Multis bury and unbury shells constantly; gravel prevents this behavior and stresses them
• Not compatible with anything that threatens the shells. Larger cichlids, loaches, and catfish that investigate shells will be attacked by fish a tenth their size

Origin and habitat

Neolamprologus multifasciatus, the multi or shellie, is a tiny shell-dwelling cichlid endemic to Lake Tanganyika and is generally reckoned the smallest cichlid in the world. Boulenger described it in 1906. It lives at depths of roughly five to fifteen metres over sandy beds carpeted with the empty shells of the snail Neothauma tanganyicense, which the lake's alkaline water has preserved in vast numbers over thousands of years. Each fish lives, sleeps, and breeds inside a shell, burying and shifting it about in the sand, and defends it fiercely against neighbours while the colony together fends off outsiders. Wild males reach only about 3 cm and females less still, though aquarium fish run a bit larger, to around 5 cm. The body is light brown with fine dark banding and a bright blue-white iris. Despite their size they live in complex colonies, a dominant male with several females and their young, and tolerate close neighbours as long as everyone has a shell of their own. IUCN lists the species as Least Concern.

Breeding

Breeds readily and is one of the most absorbing breeding fish in the hobby. Given a cluster of empty snail shells, escargot shells from a shop work as well as the natural Neothauma, a male sets up a colony and entices females to take up individual shells. Each female lays a small clutch, on the order of five to twenty eggs, deep inside her shell, the male fertilises them, and she guards from the entrance. The fry emerge after about ten days as miniature adults and stay near the shells. A colony settles into a hierarchy where the dominant pairs breed and subordinates wait, and numbers build steadily, so the group fills whatever space it has.

Common problems

Two things are non-negotiable: shells and the right water. Without empty shells the fish cannot breed or feel secure, so two or three per fish is the minimum, and the bottom must be sand so they can bury and rearrange them, which they do constantly. The water has to be hard and alkaline to match Lake Tanganyika. Beyond that they are hardy. The main behavioural catch is that they are astonishingly aggressive for their size and will harass bottom-dwellers and even fish many times larger, so a shellie colony is best on its own or only with open-water and rock-dwelling Tanganyikans that keep clear of the shell bed.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size