The fairy cichlid is one of those fish that fools people twice. First it fools you with the looks: a slender, tan body, trailing filament fins, a blue-lipped face and a little gold spot behind the eye, all of it delicate and elegant. Then it fools you with the temperament, because Neolamprologus brichardi is a stubborn, territorial fish that will square up to something three times its size and win. I keep them because they suit my hard tap water perfectly and because a colony is genuinely fascinating to watch, but I would never sell one as a gentle community fish. If you have hard, alkaline water and a tank you can give over to a single species, read on. ...

If you have hard, alkaline tap water and you want a cichlid with real character in a tank you can actually fit in a room, a Julie is one of the first fish I would point you at. Julidochromis are slow, deliberate rock-dwellers from Lake Tanganyika, they pair up and defend a patch of rock like a tiny elderly couple, and they thrive in exactly the water that makes soft-water fish miserable. The catch, and there is one, is the pairing. Get that right and a Julie pair will sit happily in a small tank for years. Get it wrong and one fish kills the other. I have watched both happen, so let me save you the second version. ...

Most fishkeepers do not need reverse osmosis water, and a good number who buy a unit end up barely using it. That is the honest starting point, and it goes against a lot of the advice you will read. RO strips your tap water down to almost nothing, minerals, buffering and all, so you can rebuild it to whatever you like. That is genuinely useful for a narrow set of fish and a narrow set of tap water. For everyone else it is an expensive, wasteful answer to a question they do not actually have. I keep hard-water fish on hard tap water, and my RO membrane spends most of the year dry. Let me explain how I decide, so you can work out whether you are in the group that needs it or the much larger group that does not. ...

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. ...

There is no salt in any of my freshwater tanks, and there has not been for years. That is the short version, and for a healthy community tank it is also the complete version. Aquarium salt has a reputation as a general tonic, a splash of it in every tank to keep the fish perky, and that reputation is mostly leftover folklore from decades ago. It does have one genuinely useful trick, and a couple of narrow treatment roles, but the “add a bit to be safe” habit does more harm than good. Let me untangle what it actually does from what it is claimed to do. ...

Float the bag for fifteen or twenty minutes to match the temperature, then net the fish out and let it go. For most shop-bought fish, on most tap water, that really is the whole job. The elaborate hour-long drip rituals you see online are the right answer for a specific situation, and quietly the wrong answer for the ordinary one. I spent my first couple of years drip-acclimating everything because a forum told me to, and I now think some of those fish would have done better if I had just got them out of the bag sooner. Here is what actually matters, and why. ...

Hardscape is the rock and wood that gives a scape its structure, and getting it right matters more than any plant you add, because it is the part you cannot easily change later. Most guides talk about hardscape purely as design. They skip the thing that has caught me out more than once: some rock quietly changes your water chemistry. On my hard tap that is sometimes a feature and sometimes a fault, and which one depends entirely on what you are trying to keep. So this covers both, the look and the chemistry. ...