The water that the fish are packaged in has different temperature, pH, and salinity parameters than your aquarium & fish are very sensitive to even minor changes in these parameters, so proper acclimation is the key to ensuring their successful relocation.
Remember to keep your aquarium lights off for at least four hours after the specimens are introduced into the aquarium to help them further adjust. We highly recommend that quarantined new fish in a separate aquarium for a period of two weeks to reduce the possibility of introducing diseases and parasites into your aquarium and to ensure they are in optimum health before their final transition to your main display.
Dim the lights in the room where the shipping box will be opened. Never open the box in bright light. Turn off aquarium lights to avoid stress. Float the sealed bag in the aquarium for 15-20 minutes. Do not open the shipping bag at this time. This step allows the water in the shipping bag to adjust slowly to the temperature in the aquarium. After floating the sealed shipping bag for 15-20 minutes, open the bag. Add 1/2 cup of aquarium water to the shipping bag & repeat step after every 5-10 minutes until the bag not fill up with water. Net your fish from the shipping bag and release into the aquarium.
Try to introduce your new arrival fish in seperate tank Be patient – never rush the acclimation procedure. The total acclimation time for your new arrival should take no longer than one hour. Always follow the acclimation procedure even if your new arrival appears to be dead. Some fish can appear as though they are dead when they arrive and will usually revive when the above procedure is followed correctly. Keep aquarium lights off for at least four hours after the new arrival is introduced into the aquarium. In some instances, your new tank mate will be chased and harassed by one or all of your existing tank mates.