Scale Welfare · Chill-kill guide
Step 1 of 7 Welcome

Better fish, no transport losses, higher price.

This guide takes you through ice-slurry slaughter for tilapia and pangasius — a method that improves quality, eliminates fish dying during transport, and earns you more at market. Tap Next to begin.

Why chill-kill?

When fish are killed by air, struggle, or insufficient ice, you lose money in three places: at the market (lower quality), in transport (mortality), and in shelf life (faster spoilage). Cold, done right, fixes all three.

1
No transport deaths

When you transport live fish, some die on the way from stress and low oxygen. With chill-kill, your fish are already on ice — every fish you load arrives.

2
Longer shelf life

Cooling fish to near 0 °C within minutes slows bacterial growth dramatically. Properly chilled fish keep fresh for 5–7 days on ice instead of 1–2.

3
Firmer, better-looking flesh

Stressed fish use up muscle energy, which softens flesh and produces lactic acid. Quick chill = firmer texture and brighter colour.

4
Less damage from struggle

Fewer broken scales, no bruising from flapping, no torn fins — fish look better and fetch a higher price.

5
Premium and export markets

Hotels, restaurants and export buyers increasingly require humane slaughter records. This method meets those requirements.

It is also better for animal welfare — fish lose consciousness in cold water faster than in air.

Photo placeholder Side-by-side: fish slaughtered conventionally vs. ice-slurry, showing colour and firmness difference after 24 hours.
Side-by-side comparison after 24 hours on ice.

What you need

Gather these before you start. You probably already have most of them. Crushed or flaked ice works far better than block ice — see the tip below.

  • A clean tank or container sized for your batch (the next step calculates exactly how much ice you need).
  • Crushed or flaked ice. Block ice melts too slowly to cool fish in time.
  • Clean fresh water — pond water is fine if you normally use it for processing.
  • A thermometer. A cheap kitchen probe will do. You will use it to know when the slurry is cold enough to load fish.
  • A clock or timer for the 20-minute hold time.
  • An insulated cooler or styrofoam box with extra ice for transport after the hold.
  • Optional: salt (about 30 g per kg of water) keeps the slurry cold longer if your ice supply is limited.
Photo placeholder All equipment laid out: tank, ice, thermometer, timer, cooler box.
Kit ready before you start — no rushing back for things.
Crushed ice beats blocks. Crushed ice surrounds fish on every side and cools in minutes. A single ice block can take an hour to do the same job. If your supplier only sells blocks, wrap them in a clean sack and break them up with a hammer first.

How much ice do you need?

Enter your tank size, your fish, and the water temperature. The calculator returns the kilograms of ice to buy for one batch.

Ice calculator

Your tank

Your fish

Temperatures

Advanced settings

Cost (optional)

You need
kg of ice
Tank water volume
Estimated fish count
Ice to chill the water
Ice to chill the fish
Ice to keep tank cold
Subtotal
+20% safety margin
How was that calculated? Three things consume ice: cooling the water, cooling the fish, and keeping up with heat coming in from the warm air. We add 20% on top so partial melting in transport and uneven mixing don't catch you short.

Prepare the tank

Pre-cool the slurry before you catch fish. Warm water absorbs a lot of the ice you bought to chill the fish.

How to do it

  1. Fill the tank to about 80% of its height with clean water.
  2. Add ice up to roughly the same volume as the water. The bath should look slushy, not just water with ice floating.
  3. Stir or paddle for a minute to mix.
  4. Check with the thermometer. Stir again first, then dip the probe into the bath.
  5. When the reading is 1 °C or below, you are ready to load fish. This is usually 5–15 minutes — but the thermometer tells you, not the clock.
The thermometer is the trigger. Don't wait a fixed time. As soon as the probe reads at or below 1 °C, go and catch your fish. If it's still above 4 °C after 20 minutes, add more ice and re-check.
Photo placeholder Pre-cooled tank with ice and water clearly mixed; thermometer reading 0–1 °C visible in frame.
Good slurry: small ice pieces, well-mixed, thermometer below 1 °C.
Don't load fish if the bath is above 4 °C. Warm slurry stresses the fish without quickly knocking them out — the worst of both worlds. Wait, add more ice, or both.

Load the fish

Once the thermometer says the bath is cold enough, move fish from the pond straight into the slurry. The shock of cold knocks them out within a minute or two.

Rules for loading

  • Aim to get the whole batch into the slurry within about 30 seconds. Don't load slowly — the early fish suffer while the later ones warm the bath.
  • Load no more fish than will be fully covered by slurry. Fish above the surface are not chilling.
  • Total fish weight should be no more than half the weight of the water. More than this warms the bath too fast.
  • Stir the slurry once after loading so fish contact cold water on all sides.
  • Don't stack fish on top of each other — the ones at the bottom may be partly out of slurry.
Photo placeholder Correctly loaded tank: fish fully submerged, slurry visible around them, not overcrowded.
Good loading: fish covered, slurry around every fish, not overcrowded.

Hold for 20 minutes, then transport

Once the fish are in the slurry, leave them there for at least 20 minutes. The cold first stuns and then kills the fish — but the kill needs time to be reliable.

20 minutes is the minimum. Don't take fish out sooner. Earlier removal risks the fish recovering when they warm up. Longer is fine — fish stay in good condition for hours in proper slurry.

While you wait

  • Keep the tank out of direct sun.
  • Check the thermometer once or twice — if the bath rises above 4 °C, add more ice.
  • Don't add new fish to the same bath until you've removed the first batch and refreshed the ice.
  • Prepare your cooler box for transport: a layer of ice on the bottom, ready to receive the fish.

After 20 minutes — transport

Move the fish out of the slurry and into your cooler box, layered with ice on top and bottom. Do not pile them in a heap. Refresh the ice during long trips.

Sell or process within 24 hours for best price. With a proper cold chain, the fish keep fresh on ice for 5–7 days.

Photo placeholder Insulated cooler with fish layered between ice — ready for transport.
Layered transport: ice, fish, ice — never just a heap.

Common problems & fixes

Thermometer is stuck above 4 °C even after 20 minutes.

Add more ice and stir well. If you bought the amount the calculator suggested but you're still warm, your tank may be in direct sun — move it under cover. Don't load fish until the reading is below 4 °C.

A fish moves when I pull it out at 20 minutes.

It hasn't been chilled deeply enough — usually because the bath warmed up too much during loading or holding. Put it back in fresh cold slurry for another 10–20 minutes.

My ice blocks aren't melting fast enough.

Block ice cools slowly. Break it up before use — wrap the block in a clean sack and hit with a flat tool. For regular use, consider a small ice crusher.

Fish look bruised or have torn fins after.

Either you handled them too hard during loading or the tank was overcrowded. Both reduce price. Aim for a single layer of fish with slurry around each one.

Buyers say my fish "smells off" after a day.

The cold chain broke somewhere — usually during transport. Check that fish are layered with ice in transport containers, not just put in a bucket.

Can I reuse the same slurry for a second batch?

Only if you remove all fish, top up the ice to fresh-slurry consistency, and check the thermometer reads below 1 °C again. Often easier to start with fresh water and ice for the next batch.