It is important to remember that aquatic animals are sensitive to rapid changes in their environment.A sudden change in temperature or water quality can send a fish into shock.If a fish dies within a day or two after you buy it, the chances are good that it was not acclimated SLOWLY to the conditions in your aquarium.the following procedures will help a fish to adapt to the water conditions in your tank.

Please note that saltwater fish require longer acclimation:

Regardless of whether you have salt or freshwater fish,start by feeding the old fish in your tank so that they don't attack the newcomers.If you have a saltwater aquarium,or an aggressive community of freshwater fish9most saltwater aquariums can be classified as aggressive in varying degress), re-arrange the decorations in the tank to help reduce aggression toward the new fish,by changing the territories around.Turn off the aquarium lights to reduce stress.Float the UNOPENED bag of fish in your tank for THIRTY minutes.Then open the bag and roll the bag down to the level of water in the bag in the same way that you would roll up your shirt sleeves.This forms an inner- tube at the top of the bag so it will float while opened without sinking.

NOTE! If you are acclimating an eel, a wrasse,goby or any other torpedo-shaped fish,DO NOT ROLL THE BAG DOWN! These fish have a tendency to jump out prematurely into the tank.Instead, open the bag, and while acclimating,trap the top of the bag under the tank lid to keep thefish from escaping.

Freshwater:Exchange 1/4 of the water in the bag with the water in your aquarium every TEN minutes for half an hour.Then release the fish.Acclimate snails,crabs and crayfish too!.

Saltwater:exchange 1/4 of the water in the bag with the water in the aquarium every ten minutes for ONE HOUR.Then release the fish.Acclimate SW invertebrates the same way.

Larger fish may be acclimated to the aquarium using the 'drip line' method.Here, the fish is placed in a bucket set below the tank which has been filled with several inches of aquarium water.The fish in the 'stor water' is poured into the bucket.A six foot section of aquarium airline is used to statt a siphon from the aquarium into the bucket.A loose'knot' is then tied in the airline so that the water entering the bucket does so at the rate of one drop per second.After a couple of hours, the fish may be netted and added into the tank.

Yeap.the transportation also plays a big part.Esp for bettas, discus, lh,.Try to get a black newspaper to cover b4 carry the fish home.It helps the fish to settle down quickly.

Try to bring the fish back ASAP and try not to let them go under the sun/air con ;)