Tangki Kuarantin Ikan: How to Quarantine New Fish Before Adding Them

A tangki kuarantin ikan (quarantine tank) is a separate tank where new fish live for 2–4 weeks before they join your main aquarium or pond. You don't need anything fancy: a plastic tub or small tank, a filter that's already cycled, an air stone, anti klorin and a lid. During that time you watch for white spot, flukes, fin rot and other problems, and treat in the small tank instead of medicating your whole display. It's the single cheapest way to stop kenapa ikan mati moments after bringing home new fish.

Why a Tangki Kuarantin Ikan Matters in Malaysia

New fish often look perfect at the shop and still carry parasites or bacteria. Stress from packing, delivery and a new home lets those problems flare up within days.

In our warm water (often 27–30°C), parasites like white spot multiply fast. An outbreak can spread through a tank within a week.
Fish often pass through several hands: farm, wholesaler, shop, buyer. Each step is a chance to pick something up.
Koi fish and pond fish are especially worth quarantining. Treating a whole pond by volume is expensive and hard, and a sick new koi can infect fish you've had for years.

A quarantine tank doubles as a hospital tank whenever a fish in your main tank gets sick.

What You Need

Item	Notes
Tank or tub	A 1–2 kaki glass tank or a plastic tub; for koi, a large tub or fibreglass tank sized to the fish
Filter	A sponge or internal filter, ideally already seeded with bacteria
Air	An air pump and airstone; warm water holds less oxygen, and many medicines reduce it further
Lid	Stressed fish jump
Hides	A pipe section or plastic plant; avoid gravel so you can see waste and clean easily
Anti klorin	For every top-up and water change
Test kit	Ammonia and nitrite at minimum
Separate net and bucket	Don't share equipment with the main tank

How to "seed" the filter

The biggest mistake is setting up a brand-new filter on the day the fish arrive. Without bacteria, ammonia builds up in a small tank within days.

Keep a spare sponge filter running in your main tank or sump all the time. When you need it, move it to the quarantine tank.
Or squeeze some dirty sponge water from the main filter into the new filter.
Bottled bacteria products help, but aren't a full replacement for a mature sponge.

Our beneficial bacteria guide explains why this matters.

Kuarantin Ikan Baru: Step-by-Step Routine

Set up the tank with treated tap water, the seeded filter and an air stone. Match the temperature to the bag water.
Acclimatise the fish. Float the bag for 15–20 minutes, then add small amounts of tank water over another 15–20 minutes. Net the fish out; don't pour the shop water in.
Days 1–3: let them settle. Keep lights dim. Offer a little food from day 2. Some fish won't eat for a day or two.
Days 3–14: observe daily. Look for the signs in the table below. Test ammonia and nitrite every few days.
Do small water changes of 20–30% every few days with anti klorin, using a separate bucket.
Days 14–28: confirm they're healthy. If nothing shows up and the fish eat well, they can move to the main tank. For koi and expensive fish, many keepers do the full 4 weeks.
If something appears, treat in the quarantine tank and restart the clock after the last symptom disappears.

What to Watch For

Sign	Possible problem	First step
White salt-like dots	White spot (ich)	See the white spot guide
Rubbing on surfaces, fast breathing	Flukes or other gill parasites	Check gills; consider an anti-parasite treatment
Frayed, white-edged fins	Fin rot or bacterial infection	Improve water, then antibacterial treatment
Cotton-like tufts	Fungus	Antifungal treatment, clean water
Red sores (common in koi)	Bacterial ulcer	See our penyakit ikan koi guide
Visible worms or "lice"	External parasites	See our kutu ikan guide
Not eating after 3–4 days	Stress, water, illness	Test water, try other foods

Should You Treat Preventively?

Some keepers give a "just in case" treatment to every new fish. Others only treat when they see a problem. Both approaches are used:

Observe-only: less stress and fewer chemicals. Works well for hardy fish from a known seller.
Prophylactic: some keepers use a low dose of garam ikan (aquarium salt) for freshwater fish that tolerate it, or a general anti-parasite medicine for koi and goldfish. Always follow the product label, and never combine medicines without checking they're compatible.

Avoid salt for sensitive fish like corydoras, some tetras and scaleless fish, and never use medicine on shrimp or snails unless the label says it's safe. Our aquarium salt guide covers safe uses.

You'll find treatments on the ubat ikan (medication) page.

Quarantine for Koi and Pond Fish

Use a tub or tank sized for the fish. Large koi need hundreds of litres, so many keepers use fibreglass or canvas tanks.
Quarantine at least 3–4 weeks.
Keep the quarantine tub away from the pond and use separate nets.
Add new koi to the pond only when they're eating well and showing no symptoms.

Plants, Shrimp and Snails

New plants can bring snails, planaria or pesticide residue. Rinse them well and, ideally, keep them in a separate container for a week or two. Shrimp and snails can be quarantined too, but use no medicines unless labelled invertebrate-safe.

Common Quarantine Mistakes

Using a brand-new, unseeded filter (ammonia spike)
No lid (jumping)
No air stone in warm water
Sharing nets and buckets with the main tank
Moving fish after only a few days
Medicating blindly without knowing what you're treating

Frequently Asked Questions

Berapa lama perlu kuarantin ikan baru? Sekurang-kurangnya 2 minggu, dan sebaiknya 4 minggu untuk ikan koi atau ikan yang mahal. Jika ada tanda penyakit, rawat dan mulakan semula kiraan selepas tanda terakhir hilang.

Perlu ke tangki kuarantin untuk ikan guppy atau ikan laga? Ya, sebaiknya. Ikan murah pun boleh membawa penyakit seperti white spot yang boleh merebak ke semua ikan dalam akuarium utama. Tangki kuarantin kecil 1 kaki sudah memadai.

Can I use a plastic tub as a quarantine tank? Yes. A clean food-safe or aquarium-rated plastic tub works well and is easy to store. Add a lid, a seeded filter and an air stone.

Do I need a heater in the quarantine tank? Usually not in Malaysia. Match the bag temperature to room temperature, and avoid placing the tank in sunlight or a cold aircond draft.

What's the difference between a quarantine tank and a hospital tank? They're the same setup. A quarantine tank holds new fish; a hospital tank holds a sick fish from your main tank. One spare tank can do both.

Set up your quarantine tank before your next fish purchase. Browse plastic tanks and tubs, internal filters and fish medication from Malaysian sellers on FishyHub.