Guides

The long answers — written out properly, so you can read them before you need them.

• Ammonia spike: the 24-hour plan when fish are gasping

  Fish at the surface, red gills, a reading above zero — ammonia is the aquarium emergency that kills fastest and is easiest to fix. What to do in the next hour, the next day, and the next week.

• Cloudy aquarium water: what each colour means and how to clear it

  Milky 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.

• Fin rot: why the fins are fraying and how to stop it

  Ragged, shrinking fins with a white or red edge are a bacterial infection with a water-quality cause. Here is how to tell it from nipping, and the two-part fix that actually works.

• White spot disease (ich): how to recognise it and treat it

  Tiny white grains on the fins and body, flashing against the gravel, then gasping — ich is the most common fish disease and one of the most curable, if you understand its life cycle.

• How to start a new aquarium

  A 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.