Setting Up a Shell-Dweller Tank: A Nano Tanganyikan Done Right

If your tap runs hard and alkaline, a shell-dweller colony is the easiest brilliant tank you will ever keep. Give them a shallow, wide footprint, a good depth of fine sand, a pile of empty snail shells and water left more or less as it comes out of my sort of tap, and they get on with living. Mine spawn in a tank I barely interfere with. I have fought soft-water species for years and lost; shellies were the first tank where the water was already right and I just had to stop meddling. Here is how I build one.

Why shell-dwellers suit hard water

Shell-dwelling cichlids come from Lake Tanganyika, which is old, mineral-rich and strongly alkaline. The lake sits around pH 8.5 to 9 with plenty of carbonate hardness, so the fish are built for exactly the water most of us with chalky tap are stuck with. My tap is roughly 22 to 23 dGH with a pH around 7.2 to 7.4. The general hardness is more than enough for these fish; if anything it is generous. The one gap is that my tap pH sits a little below where they are happiest, so I nudge it up with buffering rather than softening anything down. If you are not sure what your own numbers mean, the GH and KH explainer is the place to start.

The short version: soft-water keepers have to work to keep shellies happy, and we do not. That is the whole appeal.

The tank: footprint beats litres

The single most important thing with shell-dwellers is floor space, not volume. These are bottom-hugging fish that claim territory by the square centimetre of sand, not by the height of the water column. A tall tank wastes everything above the first 20cm. A long, shallow tank gives you more real estate where it counts.

For a starter colony of the smallest species, Neolamprologus multifasciatus, a tank of about 40 to 60 litres with a decent footprint is plenty. Something in the 60cm by 30cm range is a lovely multi tank. The slightly larger shellies, Lamprologus ocellatus or Neolamprologus similis, want a bit more floor each, so I would give them the larger end of that or step up to a 75cm tank. If you want to sanity-check your volume before you buy, the volume calculator takes the guesswork out, and the stocking calculator will stop you talking yourself into too many fish in too small a box.

Lid it properly. Shellies are not notorious jumpers, but startled fish go somewhere, and an open rim over hard water also means limescale creep up the glass.

The book behind Lagonia

The Hard Water Aquarium

My practical guide to working with hard, alkaline tap water instead of fighting it: reading your water, choosing and setting up the tank, and keeping and breeding the fish that thrive in it, from livebearers to Rift Lake cichlids and shell-dwellers.

Read on Kindle Paperback

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Get the water right (mostly by leaving it alone)

On hard tap like mine the water is already most of the way there. What I add is stability at the top end of the pH range. Tanganyikans like it buffered hard: a high, steady KH that holds pH up around 8 and does not drift. I get there with calcium-rich substrate and a Rift Lake buffering approach rather than any chemistry-in-a-bottle pH chase, which never holds anyway. The full method is in buffering hard water for Rift Lake tanks.

A few honest numbers, and remember these are guides, not laws, because tanks and test kits vary:

• GH: 10 to 20 dGH is the usual target. My tap exceeds that and the fish do not mind in the least.
• KH: keep it high, 10 dKH or more, so the pH stays put.
• pH: anywhere from 7.8 to 8.6 is fine. Steady matters more than the exact figure.
• Temperature: 24 to 26C.

If your tap is soft rather than hard, you would remineralise up to these numbers; the remineralise calculator works out the dose. And no, you do not need RO water for this tank. For most hard-water keepers buying an RO unit for shellies is money spent solving a problem you do not have, which I go into in do you need RO water.

Sand and shells, the two things they cannot do without

The substrate must be sand, and a good depth of it. Shell-dwellers dig constantly: they excavate pits around their shells, bury the shell to the angle they want, and shift sand to mark boundaries. Give them at least 5cm, deeper if you can, so they have something to actually move. Fine sand, natural in colour, inert or lime-based. I go into exactly what to use and how deep in sand for shell-dwellers, because it is worth getting right once.

Then the shells. Each fish wants its own, with spares to argue over, so budget two to three shells per fish minimum. Escargot shells from a deli are the classic cheap option and they are a good size for multies. Sizing the shell to the fish, prepping them and how many to scatter is its own small subject, covered in the best shells for shell-dwellers. Resist the urge to tidy them into neat rows. A loose, slightly messy pile with a bit of open sand between clusters gives the colony sightline breaks and reduces squabbling.

Filter, heater and flow

Shellies come from a calm sandy basin, not a torrent, so you want gentle filtration. A simple air-driven sponge filter is my default for these tanks: it will not blast the sand around, it is cheap to run, and it gives the bacteria plenty of surface. A small internal with the flow baffled works too. Whatever you use, point it so it does not scour a crater in your carefully laid sand.

A standard heater set to 25C is fine. Size it to the tank rather than guessing; the heater calculator gives you the wattage. If you are curious what a small tank like this actually costs to run month to month, the running cost calculator will tell you, and the honest answer for a nano is “not much”.

Cycle it before a single fish goes in

None of the above matters if the tank is not cycled. A shell-dweller colony puts a modest but real bioload on a small volume, and a nano tank has little margin for an ammonia spike. Do a proper fishless cycle first so the filter can handle waste from day one. If that is new to you, fishless cycling walks through it step by step. It takes a few weeks and it is the least glamorous part of the whole build, but skipping it is how beginners lose their first fish.

Stocking: buy a colony, not a pair

Multifasciatus in particular are colonial by nature, living in loose family groups over shell beds. Buy a group of six to eight young fish and let them pair and sort out their own territories as they mature, rather than trying to hand-pick a pair. Ocellatus and similis are a touch more territorial and often kept as a single pair or a trio in a smaller footprint, with more sand between shell clusters.

Keep it a species tank to start. The temptation to add “just a couple” of something else is strong, and most community fish are the wrong call here: they either bully the shellies off their shells or get harried themselves. There are a few fish that genuinely work as dithers above a shell bed, and I have been honest about the short list in what can actually live with multies. If in doubt, a single-species colony is never the wrong answer.

Settling in, and the honest bit

The first week is quiet. New shellies sulk in a shell and barely show themselves, and that is normal. Resist poking about. Feed lightly, keep the lights gentle, and within a fortnight they start claiming territory and the colony comes alive.

I will be straight about where I went wrong early on. My first attempt had sand too shallow, maybe 2cm, and the fish never settled because they could not dig their pits properly. The fix was boring: tear it down, add more sand, start again. Since then the rule in my fishroom is more sand than looks necessary. The other mistake was impatience over breeding. If a healthy colony is not spawning, it is almost always age, overcrowding or a touchy male, not your water; I pulled that apart in why shell-dwellers will not breed.

Keep up small, regular water changes, 20 to 25 per cent a week, matched for temperature and topped back up to your buffered numbers. A steady maintenance rhythm, laid out in the maintenance schedule, keeps a nano like this ticking over with very little drama. Do that, leave the water alone otherwise, and a hard-water tap you might have spent years cursing turns into the best possible excuse to keep one of the most characterful little fish in the hobby. For the bigger picture of a mixed Tanganyikan display, the Tanganyika tank setup guide picks up where a single-species shellie tank leaves off.