Guides
The long answers — written out properly, so you can read them before you need them.
Setting up a tank
- How to start a new aquariumA six-week, fishless plan for cycling your first tank — what to buy, what every reading means, and how to know the day it's safe to add fish.
- New tank syndrome: fish in an uncycled tank, and how to get them through itFish added days after the tank was filled are living through the nitrogen cycle. The daily routine that keeps them alive for six weeks, and when it is over.
- How many fish can I keep? Stocking for 20–200 litre tanksHow many fish for a 20, 30, 60, 100 or 200 litre tank, worked out by adult size and waste, not inch-per-gallon. Plus the nitrate reading that says stop.
- How to set up a quarantine tank, and why every disease guide sends you hereA bare 20-litre tank with a sponge filter is the cheapest insurance in fishkeeping: what to buy, and the four-week routine that keeps ich out of your tank.
- A first aquarium for a child: what actually worksThe kit with the cartoon on the box is the hardest tank to keep alive. What to buy instead, which fish survive a child, and the jobs a child can own.
Water and chemistry
- Aquarium water parameters: what the numbers meanAmmonia, nitrite, nitrate, pH, KH, GH and temperature: the safe ranges for a freshwater tank, what each reading is telling you, and which ones to act on today.
- Aquarium water changes: how much, how often, and whyHow much water to change and how often: the arithmetic of dilution, letting your test kit set the schedule, and how to do it without hurting the fish.
- Ammonia spike: the 24-hour plan when fish are gaspingGasping fish, red gills, a reading above zero: ammonia kills fastest and is easiest to fix. What to do in the next hour, the next day and the next week.
- Cloudy aquarium water: white, green or brown, and the fixMilky white, green, or a brown tint — cloudy water is three different problems with three different fixes, and only one of them is dangerous to your fish.
Fish health
- Why is my fish not eating? Causes and what to do todayFish won't eat? A new fish skipping food for 1–3 days is normal; an established fish refusing two meals needs a water test today. The checks, in order.
- Fish gasping at the surface: causes and what to do nowFish gulping at the top of the tank are short of oxygen or have damaged gills. The ten-minute routine, and how to tell low oxygen from ammonia or heat.
- White spot disease (ich): how to recognise it and treat itTiny white grains, flashing, then gasping: ich is the most common fish disease and one of the most curable if you outlast its life cycle. How to treat it.
- Velvet disease: the gold dust you need a torch to seeA fine gold or rust dusting with flashing and fast breathing is velvet, a gill parasite deadlier than ich. How to spot it, and the darkness-plus-copper cure.
- Fin rot: why the fins are fraying and how to stop itRagged, shrinking fins with a white or red edge are a bacterial infection with a water-quality cause. How to tell it from nipping, and the two-part fix that works.
- Columnaris: the cotton mouth that is not a fungus, and moves fastGrey-white patches on the mouth or a saddle across the back: columnaris is a fast bacterial infection, not fungus. How to tell them apart, and how to treat it.
- Dropsy in fish: pinecone scales, causes and treatmentSwollen body, scales raised like a pinecone: what dropsy means, the Epsom salt and antibiotic plan that can save an early case, and when to stop.
- Swim bladder disorder: fish floating, sinking or sidewaysA fish stuck at the top, on the bottom or on its side: the five causes of swim bladder trouble, the fast-and-pea fix, and when it needs more.
- Popeye in fish: bulging eye causes, treatment and recoveryOne bulging eye is usually an injury; both means the water or an infection. How to tell which, the Epsom salt fix, and how long the eye takes to heal.
- Cloudy eye in fish: the water problem behind the filmA milky film over one or both eyes is usually the water, sometimes a scratch, rarely a parasite. How to tell which, and the clean-water-and-salt fix.
Species care
- Betta fish care: the tank, the water, and the one-fish ruleBetta care in plain terms: a heated, filtered 20–40 litre tank at 25–27 °C, one betta per tank, what to feed, and the three problems every keeper meets.
- Goldfish care: the tank they actually need, and why the bowl killsA goldfish is a hand-sized carp that lives twenty years and makes more waste than any tropical fish. The tank, filter, feeding and water routine it needs.