Quarantine sounds like an “advanced hobby” thing, but it’s actually one of the simplest habits that saves the most money and stress. Most problems in guppy tanks begin the same way: a new fish arrives, looks fine for a few days, then something shows up — spots, fin damage, parasites, or sudden losses. If that fish goes straight into the main tank, the whole system becomes the quarantine. A dedicated quarantine setup prevents that.
What quarantine actually needs
- Tank: even 20–40L is enough for a short holding period.
- Filter: a sponge filter seeded from a mature tank is ideal.
- Heater: stable temperature reduces stress and improves immune response.
- Simple decor: a small hide is fine, but keep it easy to clean.
How long to quarantine?
A common practical window is 2–4 weeks. That’s long enough for many issues to show themselves. If you buy fish from different sources, quarantine also prevents mixing microbes and stress patterns in the main tank.
What to watch during quarantine
- appetite and confidence at feeding time
- fin condition and any fraying
- flashing or rubbing behaviour
- white spots, redness, ulcers, or rapid breathing
Do you have to medicate in quarantine?
Not always. Many people quarantine as observation first. Medication is most effective when you have a symptom pattern and stable water. The biggest advantage is that if you do treat, you treat a small tank without stressing the display system.
Quarantine doesn’t need to be complicated. It just needs to exist. A simple quarantine tank is the difference between one fish having an issue and your entire tank becoming an emergency project.
