Do regular partial water changes
Use dechlorinated, temperature-matched water
Reduce feeding
Remove uneaten food
Clean gravel and substrate
Vacuum the tank bottom
Avoid overstocking
Add more live plants
Use fast-growing plants
Clean filter media in tank water
Do not replace all filter media at once
Improve biological filtration
Increase tank maintenance frequency
Remove dead plant matter
Remove dead fish promptly
Test water regularly
Use nitrate-removing filter media
Consider a larger tank if needed
Rinse decorations before returning them to the tank
Avoid overuse of fertilizers and additives
Feed smaller portions more often