Many beginners think that cleaning an aquarium means taking all the fish out. This fear often stops people from cleaning their tanks properly. The truth is, you can safely clean an aquarium without removing fish, and in most cases, this is actually better for the fish.
In this guide, you’ll learn safe, simple, and stress-free ways to clean your aquarium while fish stay inside.
Why You Should Not Remove Fish Often
Taking fish out during cleaning can:
Stress them badly
Damage their slime coat
Cause injuries or shock
Change water temperature suddenly
Fish feel safest in their own tank. Frequent removal is unnecessary and harmful.
How Often Should You Clean an Aquarium?
For a beginner tank:
Light cleaning: every week
Partial water change: once a week (20–30%)
Deep cleaning: once a month (never full clean)
Remember: cleaning does not mean making everything spotless. Some beneficial bacteria must stay.
Things You Need Before Cleaning
You don’t need expensive tools.
Basic items:
Clean bucket (only for aquarium use)
Siphon or pipe
Algae scrubber or clean sponge
Dechlorinated water
Towel
Never use soap or household cleaners.
Step 1: Turn Off Electrical Equipment
Before cleaning:
Switch off filter
Turn off heater
This prevents damage and keeps you safe.
Step 2: Clean the Aquarium Glass
Use:
Algae scraper
Magnetic cleaner
Soft sponge
Gently remove algae from:
Front glass
Side glass
Do not scrub too hard. Leave some algae on back glass—it’s natural and harmless.
Step 3: Partial Water Change (Most Important Step)
This is the safest way to clean a tank.
How much water to remove?
Small tank: 20%
Medium tank: 25%
Dirty tank: Max 30%
Never remove all water.
How to do it:
Use a siphon or pipe
Remove water slowly
Fish will move away naturally
This removes waste without disturbing fish.
Step 4: Clean the Gravel Without Removing It
While siphoning:
Push pipe slightly into gravel
Let dirt come out
Do small sections only
Don’t clean all gravel at once. Beneficial bacteria live there.
Step 5: Cleaning Decorations (Inside the Tank)
If decorations have algae:
Gently scrub inside the tank
Or remove one decoration at a time
Never clean all decorations together.
Avoid soap at all cost.
Step 6: Filter Cleaning (Very Important Rule)
Many beginners make a big mistake here.
Never wash filter media under tap water.
Correct way:
Take some tank water in a bucket
Gently squeeze sponge in that water
Put it back
This protects good bacteria that keep fish alive.
Step 7: Add Fresh Water Carefully
New water should be:
Same temperature as tank
Treated with water conditioner
Pour water slowly so fish don’t get shocked.
Step 8: Turn Equipment Back On
After cleaning:
Turn filter on
Switch heater back on
Watch fish for a few minutes. They usually swim calmly if everything is done right.
Common Beginner Mistakes to Avoid
❌ Removing fish every time
❌ Changing 100% water
❌ Washing filter under tap
❌ Using soap or chemicals
❌ Cleaning too often
These mistakes cause more harm than dirt.
How Fish React During Cleaning
Normal behavior:
Swimming away from siphon
Curious movement
Calm swimming after cleaning
Warning signs:
Gasping at surface
Panic swimming
Lying at bottom
If this happens, stop cleaning and check water temperature.
How to Keep Tank Cleaner for Longer
Simple habits:
Don’t overfeed
Remove uneaten food
Keep proper fish count
Do weekly partial water changes
Less dirt = less cleaning stress.
Final Thoughts
Cleaning an aquarium without removing fish is not only possible, but recommended. It keeps fish calm, protects beneficial bacteria, and maintains a healthy tank.
For beginners, the golden rule is:
Clean gently, change water partially, and never rush.
A calm approach keeps both the tank and fish happy.