Your new fishes have just arrived. Either bagged and picked up from one of us or when you unwrap your postal christmas present. You are excited and want to plop these fishes into their new homes right away but you KNOW there are steps you need to take before that happens.
There are two main reasons that you cannot just drop them in your new tank, pH shock and temperature shock. These can stress out and even kill your fishes. pH shock is when you add fishes directly into a tank with a large pH difference than where they came from. ie. adding a betta with pH 6.0, instantly into a tank with 8.0 pH can defintely traumatize your fish. Temperature shock is similar but with large differences in temperature.
Most people have been taught how to prevent temperature shock by floating the bag into their new home for 15 minutes so that the water can adjust to similar temperatures before release. However, nobody teaches the public about pH shocks.
This is something that goes unnoticed as it may not happen instantly and your fish may die from this shock several days later leaving you distraught and confused. A lot of times when healthy fishes have died within a week in your tank, it may very likely be from pH shock.
How can you fix this? Some say to pour some of your tank water into their bag as you float it. I would do this with fishes that aren’t as sensitive and with pH almost similar to my tank. I would double the water in the bag with tank water and float for 10 minutes, pour out half down the drain (not into the tank) and double the water in the bag again. I repeat this process about 3-4 times and then scoop the fishes out. I do not keep any of the water in which the fishes came because I usually do not trust the source.
A safer method that is essential for sensitive fishes would be the drip acclimation method. This is a method where I would use an airline tube with an adjustable valve and siphon water slowly from the new tank into a container holding the new fish. Flow rates can be as slow as one drop per second and increase over time. This would be done until the pH in the container matches the pH in the new tank. Then bag the fish up or float the container until the temperatures match. If there is a big difference in water parameters, you can even slow it down to one drop every 3-5 seconds.
Water from existing aquarium being dripped to small container with new fish. An air stone is used to prevent any small fishes or fry from getting sucked into the tube.
A ball valve is used to adjust the flow of water to your new fish.
This concept is so common for intermediate and experienced hobbyist that it has became the norm and that we tend to forget there are still many out there who are beginners just starting out in the aquarium hobby. We would like everyone equally to have the best success in keeping fishes! It’s a fun and rewarding hobby when we give our fishes the best chance of survival!