Species

Guppies are hardy in the ways that matter for a beginner, and fragile in a couple of ways nobody warns you about. That is the honest short version. They will forgive a wobbly first month, a slightly late water change and a filter that is not quite up to spec, which is exactly why they earned the reputation. What they will not forgive is soft, mineral-poor water and a tank of sick shop stock, and modern fancy strains are noticeably less bulletproof than the guppies of twenty years ago. I keep livebearers on very hard tap water, and I have watched cheap guppies shrug off things that flattened fussier fish, and I have also watched a batch of pretty fancy ones melt away for no obvious reason. Both things are true. Here is how to tell which guppy you are actually buying. ...

If you are choosing between multies and similis for your first shell-dweller tank, here is the practical steer: get whichever your shop actually has, correctly labelled, because the two are so alike in what they need that the choice barely changes your setup. If both are in front of you, I would nudge a first-timer towards multies, mostly because they are easier to find and a fraction more forgiving. But this is a close-run thing between two lovely little fish, so let me lay out where they actually differ rather than pretend one is plainly better. I keep both on hard tap, and I still catch myself squinting at the glass to tell which tank I am looking at. ...

The short answer is empty escargot shells, and more of them than you think. If you buy a bag of catering-grade escargot shells, boil them, and scatter roughly three or four per fish across the sand, you have already done the single most important thing for a happy shell-dweller colony. Everything else on this page is refinement. I run my multies and similis on very hard tap water in shallow, wide tanks, and after a few years of fiddling with different shells I have landed on a setup that keeps the fighting down and the breeding up. Here is what actually works. ...

The question I get asked most about my multi colony is what else I keep in with it. The honest answer, in the tank I actually run, is nothing. It is a species-only tank on a bathroom shelf, around fifty litres of hard tap water, sand, a heap of escargot shells and a self-running colony of the smallest cichlid in the world. That is not me being unadventurous. It is the conclusion I came to after thinking hard about what a tankmate is really for, and what it costs the colony to have one. ...

Swordtails were one of the first fish I kept that felt like they had actual personalities. Where a shoal of tetras drifts around as a single nervous cloud, a group of swordtails will stake out territory, chase each other about, and come barrelling to the front glass the second you walk past. The males carry that unmistakable sword trailing from the bottom of the tail, and a mature red male against a dark background is a genuinely striking thing. Best of all for anyone reading this site, they want exactly the water that comes out of my tap. If you keep hard alkaline water and you want something with a bit more presence than a guppy, swordtails deserve a serious look. Here is how I keep mine. ...

If you keep hard tap water and you want a splash of colour that will not sulk in it, Endler’s livebearers are one of the best small fish you can buy. I picked up my first group almost by accident, a handful of unlabelled males in a bag from a local keeper, and they turned a quiet 40 litre into something that stopped visitors mid-sentence. The males look like someone dipped a guppy in metallic paint and then shrank it. They are cheap, hardy, endlessly active, and they thrive in exactly the water that makes soft-water darlings like cardinal tetras miserable. This is how I keep them, what they actually need, and the one habit that will save you a lot of grief later. ...

If you have hard, alkaline tap water and you want a tiny cichlid that runs its own colony in a small tank, Neolamprologus similis deserves a place on your shortlist right next to its famous cousin. Similis is a shell-dwelling Tanganyikan, one of the smallest cichlids kept in the hobby, and it does everything the better-known multifasciatus does: it digs, it defends a shell, it breeds inside it and it builds a little society across the tank floor. The main practical difference is the look and the temperament, and both, to my eye, come out slightly in favour of similis. This is the species profile: what it is, how it differs from the multi, and how to keep and breed a colony in water like mine. ...

Some fish demand careful water and a gentle hand. The zebra danio is not one of them. It is a small, striped, endlessly busy little thing that behaves as though it has drunk far too much coffee, and it is about as forgiving a fish as exists in the hobby. If you have hard tap water and want a lively shoal that adds movement to the upper half of a tank, danios deserve a serious look. I have kept them as a dither shoal in community tanks for years, and they have shrugged off conditions that would have finished more delicate species. ...

If you have hard, alkaline tap water and you want a fish that looks like a boiled sweet and behaves like it has somewhere to be, the platy is hard to beat. It sits alongside the guppy as one of the two livebearers I recommend most often to people starting out with water like mine, and in some ways I prefer it. Platies are a touch chunkier, a little calmer, and they come in colours that seem almost unreasonable for a fish you can buy for the price of a coffee. I have kept them for years, usually as the middle layer of a community tank, and they ask for very little in return. ...

If you have hard, alkaline tap water and you want a small, colourful fish that will not just tolerate it but genuinely prefer it, guppies are one of the easiest recommendations I can make. Poecilia reticulata is the fish that got most of us into the hobby, and there is a good reason it keeps turning up in beginner tanks: it is tough, it breeds without any encouragement, and the males look like someone spilled paint. I have kept them on and off for years, and the tank in my kitchen has run more or less on autopilot for the last two. ...