Problem Solving

Sooner or later most fishkeepers meet white spot, and the first time is a fright. You look at a fish one evening and it is dusted with tiny white grains, as if someone had shaken salt over it. That is ich, short for Ichthyophthirius multifiliis, and it is probably the most common parasitic disease in freshwater tanks. The good news is that it is very treatable if you understand what you are dealing with. The bad news is that people lose fish to it constantly, almost always because they stopped treating too soon. I have cleared it out of my own tanks more than once, and the whole thing comes down to respecting the parasite’s lifecycle. ...

Losing a fish is miserable, and when it keeps happening it is easy to decide you are simply unlucky, or that the hobby is not for you. In almost every case I have been asked to help with, the fish were not weak and the shop was not selling duds. Something in the tank or the routine was quietly wrong, and once it was found the deaths stopped. This is the checklist I work through with people, roughly in the order the problems tend to show up. ...

You walk past the tank one morning and the water has gone the colour of pea soup. The fish are still swimming about quite happily, the equipment is running, nothing smells wrong, and yet you can barely see the back glass. It is one of the more alarming things a new tank can do, mostly because it seems to arrive overnight and no amount of wiping the glass makes any difference. I have had it happen on new setups, on tanks that sat too near a window, and once on a tub of fry I was raising outdoors. The good news is that green water is one of the easier problems to fix once you understand what it actually is, and it very rarely hurts the fish. ...

Cloudy water is probably the most common problem I get asked about, and it is also one of the most misdiagnosed. The panicked new keeper does a massive water change, the cloud comes back worse the next morning, they change more water, and around it goes. I have run a lot of tanks over the years, from shell dweller setups to outdoor tubs, and I have seen every flavour of cloudiness there is. The good news: the colour and timing of the cloud tell you almost exactly what is going on, and most of the fixes cost nothing. The bad news, if you can call it that: the most common cause is fixed by doing less, not more, and doing less is genuinely hard when your tank looks like dishwater. ...

Every tank I have ever run has grown algae. The lovingly scaped planted tank, the bare quarantine tub, the shrimp bowl on my desk, all of them. So before anything else, let go of the idea that algae means you have failed. It does not. Algae is what happens when light and nutrients are available and nothing else is using them fast enough. The trick is not eradication, because eradication is impossible. The trick is identification. Each common type of algae points to a specific imbalance, and once you can read the signs, you can fix the cause rather than endlessly scrubbing at the symptom. ...