It sounds like your aquarium has a water quality problem
How to be sure
Your fish are unwell or may have even died suddenly with no obvious reason. Invisible nasties in the water are often the cause and can only be discovered by testing your water.
Step 1 – Treat your aquarium
- You need to test your aquarium water for excessive ammonia, nitrite, nitrate or pH imbalance.
- Treat any unhealthy results to rebalance your water quality and give your fish the best chance of getting fighting fit again.
- Check all your equipment is working properly – especially filters and heaters (check your aquarium temperature with your thermometer). Carry out any maintenance needed, or replace faulty or broken parts.