Right, I love fancy goldfish. Love them. They are chubby and ungainly and daft-looking. Some of them have eyes that bulge out of their heads and bobble around independently, while others have layers and layers of diaphanous fins that provide a ridiculous contrast to their basic spherical-ness. They are shiny.

They can be kept in a nice cheap bowl, with all the water whipped out and all the gravel given a good scrub under the tap every week, to keep it sparkling clean. Alternatively, you don’t have to clean them out at all and they will live happily in their green stagnant pool. Either way, just chuck in a good heft of food flakes daily and leave them to it! Not like those tiresome tropical or marine fish, who need expensive technology developed by NASA just to get them home from the shop, chuh, fish with ideas above their station, if you ask me, living up on nob hill with their filters and lighting systems and heaters. Goldfish: the proletarian fish! The fish for the busy working individual!

Um, not quite. They are great pets, but they are a bit more work than that. Goldfish are shit-machines, to put it bluntly. They have the ability to eat as much as they like, cramming it in with greedy abandon, hoovering it all up with glee, but only taking the nutrients that they need and dumping the rest. Their prodigous eating and pooing is only outmatched by their peeing, which contains high concentrations of ammonia.

They are also prone to about ten billion diseases: white spot, velvet, swim-bladder, fin rot, mouth rot, constipation, flukes, little parasites called ich (among others), and multiple variations of worms. There is apparently something out there that will make a hole appear in your goldfish’s head. There is the dreaded dropsy – a coldwater fish fan sees dropsy, a bacterial infection, as your average medieval inhabitant saw bubonic plague. This will cause poor fishy to swell up like a balloon and become spiky like a pine-cone. And then die.

You want a goldfish? You can have a bowl, if you want, but then you can keep your pet dog in a cupboard, if you want; you can let it live in a pile of its own poo and rotting food, if you want. It’s just not very nice.

Quick aquarium guide

So, what do you actually need?

You need water, lots of water – because they poo so much, your average goldfish actually needs more water than most other fish: about twenty UK litres per individual fish. They also like lots of surface area on that water, so a square-ish tank is better than a long thin one, even though their volume might be the same.

With regards to aquascaping, you can stick pretty much whatever you want in; luminous or natural gravel, sand, bog wood, towering gothic castles, river pebbles, corpses that spring from coffins, ruined bridges, plants of any description in silk or plastic. A general rule of thumb is that your substrate should be a couple of inches deeper at the back than at the front, and that real plants are nothing more than a pain in the arse when it comes to your average ravenous goldfish. If they don’t eat it, they’ll rip it to shreds and watch it float around. Also, real plants mean snails. This is never good.

However, before you leap into action with a bucket, one little thing: chlorine will poison your aquatic pal. Get thee to the nearest aquatic supplies shop and get yourself a declorinator. While you’re there, you’re going to have to get a filter as well. Sorry about this but you are; what with all the poo, and the wee, and the hordes of fatal germs waiting to invade at any time, you and your fish need a little something on your side. Filters, and their store of friendly bacteria, are that little something. Once it is up and running, it will break down the ammonia, move the water around, and keep your water quality high.

You can also get lights, heaters, gravel cleaners (I think these are quite handy, for what it’s worth), feeding rings, aloe vera drips, nets, reverse osmosis water filters, bubble stones, spray bars, blah blah ad infinitum. Some of these are good, and some are ways of parting credulous muppets with their cash. But, you know, whatever makes you happy. Your little golden swimming nuggets are looking a bit less minimalist now, aren’t they? Again, one thing: pretty much anything that claims to allow you to stock your tank instantaneously is a BIG FAT LIE, for the following reasons:

So you’ve got your dechlorinated water, your tank is looking swish, and the filter is in and churning away. Fish Time! Uh-uh, sorry – your tank has to sit there for a week AT LEAST, more if possible. This is to avoid the dreaded New Tank Syndrome, where the filter has insufficient bacteria to cope with the levels of ammonia, can’t break it down, and all the fish are poisoned. You can buy products that claim to have friendly bacteria suspended in them, or steal some water from an existing tank, or best of all, some filter media from an established filter, and put it in yours. Restrain your impatience, let it run for as long as possible: I’m obliged to say that really, you should buy a water testing kit and not stock your aquarium until the water levels are optimum, with zero ammonia, zero nitrate, and nitrite at less than 25ppm. But to be honest, I don’t think that I’ve ever done this if the testing kit wasn’t free.

at last…Get the fish!

A quick guide to fish would be basically useless here, as it really requires pictures and there are plenty of places on the internet that will show you those. But there are enough varieties to fulfil your heart’s desire; black, gold, white, black and gold and white, round, streamlined, ones that look just like golf balls. You can get really complicated with talk of groups and units and spec, but basically don’t stick fast thin ones with slow fat ones: the fast skinnies will steal all the food, nibble the fins, and generally harass the fatties.

And that’s it! Don’t put vodka in the tank to see if they get drunk, add fresh dechlorinated water every week but don’t change any more than thirty percent of the water at any one time, don’t overfeed and try and wet any dry food with tank water before you give it to them. That comedy floating upside-down thing they do is actually pretty bad for them…