How Do I Acclimatise Fish
Your retailer should package any fish you buy in a suitable fashion, normally double-bagged with at least two-thirds of the bag filled with air. In most cases this will keep your fish safe for up to an hour, although it is best to inform your retailer if you are travelling any longer than half an hour as they may package your fish differently.
During the journey home your fish should be kept in the dark and away from any extremes of temperature. Once you arrive home the following procedure should be followed:
Turn your aquarium lights off - this will prevent the shock of sudden bright light and kept your new fish subdued.
Float the bag for 5-10 minutes - this will equalise most of the temperature between the water in the bag and the aquarium.
Open the bag up and create a 'floating rim' of air by folding the sides down evenly - this will allow gas exchange to take place and oxygen to enter the water.
Add a little aquarium water to the bag - do this every few minutes for the next ten minutes until the volume of water in the bag has at least doubled.
Release the fish - gently tip the bag beneath the surface and slowly encourage the fish to leave the bag.
Leave the fish alone - It is best to leave lights off for at least half an hour after release and then simply leave the fish alone for the rest of the day to get settled.
Some fish can take several days to get fully settled and may be nervous, hide away, or avoid feeding during this period. This is normal and do not worry too much as long as the fish can be seen and appear healthy. To avoid stressing the fish it is best to avoid doing any maintenance for several days after adding new fish.