Fish‑Keeper’s Folly: Life Before the Lab The Age of Unmeasured Waters,

The saying “We didn’t test water in my day” usually comes from people who kept hardy fish, had fewer options, and accepted higher levels of loss. The hobby has changed a lot — and so has the understanding of fish health.

Here’s why regular water testing matters today:

1. You Can’t See Most Problems

Water can look crystal clear and still be toxic.

The biggest killers in aquariums are invisible:

 Ammonia – burns gills, lethal even at low levels

 Nitrite – prevents oxygen transport (“brown blood disease”)

 Nitrate – stresses fish long-term

 pH swings – cause shock

Before hobbyists understood the nitrogen cycle, fish deaths were often blamed on “bad luck.” Now we know better.

2. Modern Tanks Are More Stocked (and More Delicate)

Today we keep:

 Sensitive fish like discus or dwarf cichlids

 Invertebrates like shrimp (which are very parameter-sensitive)

 Reef tanks with corals that demand stable chemistry

A saltwater reef tank, for example, needs stable alkalinity, calcium, and magnesium — something rarely measured decades ago.

3. Tap Water Isn’t the Same Anymore

Municipal water supplies now commonly use:

 Chloramine (harder to neutralise than chlorine)

 Variable mineral content

 Seasonal changes in chemistry

Testing helps you understand what you’re adding during water changes.

4. Prevention Is Cheaper Than Replacing Fish

A £20 to £30 test kit can prevent:

 Fish losses

 Algae outbreaks

 Crashes in cycling tanks

It’s like checking oil in a car — not mandatory every day, but smart maintenance.

5. The Hobby Is More Science-Based Now

In the past:

 Fish were often treated as disposable.

 Losses during cycling were common.

Now:

 We fishless-cycle tanks.

 We quarantine.

 We test to prevent suffering.

The goal isn’t just “fish survive.” It’s fish thrive.

So Why Test?

You should regularly test because:

 New tanks are unstable.

 Stocking changes affect bio-load.

 Overfeeding spikes ammonia.

 Filters fail.

 Water suppliers change treatment.

Even experienced aquarists test when:

 Fish act stressed.

 Something smells “off.”

 They change equipment.

Bottom Line

They didn’t test “back in the day” because:

 The science wasn’t widespread.

 Expectations were lower.

 Fish losses were normalised.

Today, we test because we can, we understand why, and we care more about long-term fish health.

My article, "Fish‑Keeper’s Folly: Life Before the Lab," details the historical lack of regular aquarium water testing and explains why it’s so important today.