Fish Acclimatization Guide
The process of gently introducing new fish to your aquarium's conditions — the key to stress-free fish that thrive long-term.
4 Acclimatization Steps
Follow these in order — do not skip any step. Total time is approximately 30–60 minutes depending on the species.
- Place the sealed fish bag on the surface of the aquarium water.
- Leave it for 15 minutes to let the temperature inside the bag gradually equalise with the aquarium.
- Do NOT open the bag yet — this step is purely for temperature equalisation.
Turn off the aquarium light during this process to reduce stress on the fish.
- Carefully open the bag, then add approximately 200 ml of aquarium water into the bag.
- Wait 5 minutes, then repeat adding water 2–3 more times.
- This gradually equalises the pH, minerals, and chemical conditions of the water.
Use a small cup or glass to scoop aquarium water — easier to control the amount.
- Use a clean cup or fine net to gently transfer the fish into the aquarium.
- Do NOT pour the bag water into the aquarium — shipping water may carry bacteria.
- Move the fish as calmly as possible to minimise stress.
Discard the shipping bag water — do not add it to the aquarium even if it looks clean.
- Observe the fish's appetite, movement, and colouring during the first 24 hours.
- Reduce light intensity on the first day so the fish does not feel stressed.
- Delay feeding for 12–24 hours to allow proper adaptation time.
A fish hiding in corners or breathing at the surface are signs of stress — check water quality immediately.
Tips by Fish Species
Each species has different needs. Select your fish type below.
🔴 Betta (Betta splendens)
- Betta are fairly tolerant of water changes compared to Discus or Arowana.
- 20–30 minutes of acclimatization is sufficient — do not extend it as oxygen in the bag is limited.
- Betta must never be kept together with other males — prepare separate tanks.
- A stable temperature of 26–28°C is important for immunity. Avoid placing near air conditioning or draughty windows.
- After release, delay feeding for 12 hours to allow the fish to settle first.
🟡 Discus (Symphysodon)
- Acclimatize for a minimum of 45–60 minutes. Longer is safer for Discus.
- The aquarium temperature must exactly match the bag temperature before opening.
- Your aquarium must be fully cycled with stable parameters for at least 2 weeks before the Discus arrives.
- Use RO water or treated water — Discus do not tolerate raw tap water.
- Dim lighting for the first 3–5 days is strongly recommended.
🟢 Arowana (Scleropages)
- Acclimatize for 30–45 minutes. Arowana are more tolerant than Discus but still need gradual adaptation.
- The tank must have a secure, heavy lid — Arowana are powerful jumpers and can escape.
- pH of 6.5–7.0 is ideal; avoid pH above 7.5 long-term.
- Do not keep with small fish that can be swallowed. Arowana are surface predators.
- Delay first feeding for 24–48 hours after full adaptation.
🦐 Ornamental Shrimp (Neocaridina / Caridina)
- Use the drip acclimatization method (drop by drop) for 1–2 hours for best results.
- Use a small airline tube with a knot/valve to slowly drip aquarium water into the container holding the shrimp.
- Never use products containing copper sulphate in a shrimp tank.
- Stable pH is more important than hitting an exact number — a sudden pH crash is lethal; gradual fluctuation can be tolerated.
- *Ideal pH varies by species: Neocaridina 7.0–7.5; Caridina (Crystal/Taiwan Bee) 6.0–6.8.
🚿 How to Do Drip Acclimatization
- Pour the shrimp + bag water into a separate bucket or container.
- Attach an airline tube with a flow-control knot from the aquarium to the shrimp container.
- Adjust the flow to approximately 2–3 drops per second.
- Wait until the water volume in the container is 3× the original amount (approx. 1–2 hours).
- Transfer shrimp using a spoon or net, then discard all the water in the container.
Warning Signs & Solutions
Recognise the signs of stress in new fish so you can act quickly.
Signs of Stress / Danger
- Breathing continuously at the water surface
- Pale colouring or uneven patches
- Swimming in circles or listing to one side
- Sitting motionless in a corner for hours
- Fins constantly clamped to the body
Signs of Healthy Adaptation
- Actively swimming and exploring the tank
- Bright, even colouring after 24 hours
- Eating willingly by day 2 or 3
- Normal breathing — not at the surface
- Fins fully spread with smooth movement
💊 What to Do If Your Fish Shows Signs of Stress?
Check temperature — ensure it is at the correct range for the species
Test ammonia & nitrite with a test kit — zero is the safe reading
Turn off the light and reduce disturbances around the tank
Perform a 20–30% water change with fresh, conditioned water
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Need Help?
Our team is ready to assist with acclimatization, water quality, or care for your new fish.