GUIDES
What to test first (and what numbers matter)
Before you treat anything: test these in order. Most “mystery” symptoms start with water.
1) Ammonia & nitrite (any reading is a problem)
- Goal: 0 ammonia, 0 nitrite
- If present: water change + detox + aeration is the priority.
- Re-test in a few hours, then daily until stable.
2) pH (and stability)
- Goal: stable day-to-day more important than a “perfect” number.
- Check pH at night and again in the morning if fish are flashing.
- Big swings usually mean low KH (alkalinity).
3) KH / Alkalinity (the stability battery)
- Goal: enough KH to prevent daily pH swings.
- Low KH can cause flashing, stress, poor healing, and “random” behavior.
- How to fix it safely: see the KH/pH guide →
4) Temperature
- Temperature controls parasite activity, immune response, and what treatments are safe.
- When it’s cold, fish heal slower and many “fast” fixes don’t work as well.
5) Quick sanity checks
- Any recent changes? new fish, big cleanout, filter disturbance, big water change.
- Aeration: too little or too much microbubble irritation can trigger symptoms.
- Chlorine/chloramine exposure after water changes can cause immediate distress.
When to treat meds
- If ammonia/nitrite are present: treat water first.
- If water is stable and symptoms persist: move to symptom triage or parasite workflow.
- Don’t combine treatments unless you’re following a known compatible plan.