BettaGuideWater

How to change your betta's water (step by step)

Kawaii Tomodachi Pets · Molino, Bacoor ·

Comic thumbnail: Momo with a bucket and Hanabi, with the words Water change day

Clean water is the biggest thing you can do for your betta. Dirty water is behind most dull, tired or sick bettas. The good news: a water change takes about 10 minutes once you know the steps.

Momo

MomoWater-change day helper

Hanabi

HanabiLikes his water fresh

Momo fills a small bucket with tap water
Step 1: fill a clean bucket.
Momo adds drops of anti-chlorine from a small bottle into the bucket
Step 2: anti-chlorine. Every time!
Momo takes old water out of the tank with a siphon tube while Hanabi watches
Step 3: take out the old water.
Momo pours the new water in slowly and Hanabi swims happily
Step 4: pour in slowly. Done!
½of the water, small tanks
3 daysbetween changes, small tanks
¼weekly, 5 gal with filter
100%of new water gets anti-chlorine
How much, how often

Find your tank

4x6x8 or 6x6x8

Change half the water every 3 days.

2.5 gallon

Change half the water every 3 days.

5 gallon with a gentle filter

Change about a quarter of the water once a week.

Smaller tanks get dirty faster, so they need changes more often. Not sure which size is right? Read What tank size does a betta need?

Step by step

How to do a water change

  1. Fill a clean bucket with tap water. Use a bucket only for the fish. Never one that had soap or detergent in it.
  2. Add anti-chlorine. Follow the dose on the bottle. Tap water has chlorine that hurts fish, so this goes in every bucket, even for small top-ups.
  3. Check the temperature. The new water should feel the same as the tank water. Let it sit in the same room for a while if it feels cold.
  4. Take out the old water. Use a siphon or a cup. Pick up poop and leftover food from the bottom while you're at it. Your betta can stay in the tank.
  5. Pour in slowly. Pour against the glass or onto a plant so you don't blast your betta with a wave.
Momo dips her hand in the bucket to feel the water temperature
Same temperature? Good.
Momo pours water gently onto a plant leaf in the tank, Hanabi calm
Gently, onto a plant.
Avoid these

Common mistakes

Momo pushes a bottle of dish soap away from the fish tank
No soap. Ever.
  • Skipping anti-chlorine "just this once".
  • Soap or detergent on the tank or decor. Rinse with plain water only.
  • Changing all the water at once in a set-up tank. Big sudden changes stress him.
  • Very cold or very warm new water.
  • Waiting until the water looks dirty. Water can be bad before it looks bad.
Hanabi says
Hanabi says

Clean water keeps my colours bright and my fins strong. If I look pale, check my water first. More in Why is my betta losing colour?

From our shop

What we use for water changes

Amazon Meds Anti-Chlorine Water Conditioner 150mlAnti-chlorine

Makes tap water safe. 150 ml bottle.

Aquarium siphon gravel cleanerSiphon

Takes out old water and dirt without moving your fish. 170 cm siphon.

Fine mesh aquarium fish netFine net

For scooping leftovers, gentle on fins. Fish net.

See the fish in our betta collection.

FAQ

Questions customers ask us

Can I use tap water for my betta?

Yes, as long as you add anti-chlorine first. Without it, the chlorine in tap water can hurt your fish.

Do I take my betta out during a water change?

No need for a normal partial change. Leave him in and pour the new water in slowly.

The water is still clear. Do I still change it?

Yes. Waste builds up in the water even when it looks clean. Keep to the schedule for your tank size.

Should I let tap water sit overnight instead?

Use anti-chlorine. It works right away, so you don't have to guess.

Do I need a filter?

Not for small tanks if you keep to the water-change schedule. A 5 gallon tank with a gentle filter needs fewer changes. Strong currents tire bettas out, so keep it gentle.

The cartoons show our characters Momo and Hanabi. Water-change amounts are from our betta care guide.