Article in English: Before you do this, make sure the bag has enough air so the betta can breathe. Letting the bag float at the top of the betta’s new tank will allow the water in the bag (with the betta in it) to match the temperature of the water in the tank.  This process is known as “floating” the betta. Let the bag sit in the tank for 10–15 minutes. Once the bag has floated in the fish tank for about 15 minutes, you can start to expose your betta to the water in the fish tank. Use scissors to cut a hole in the bag. Using a baster or a small cup, pour about a cup of the tank water into the bag. You’ll need to stand there and hold the bag upright during this time. If you release the bag or let it tilt too far to one side or the other, the water will spill out into the tank. Your betta needs this time to slowly adjust to the temperature, pH level, and mineral hardness of the water in the tank. If you rush these steps and do not give your betta time to acclimate to the water, it will be harmful to the fish’s health.  Repeat the step one more time: mix another cup of tank water into the bag with the betta. Continue to hold the bag in the tank during this time. Make sure to keep the cut in the bag facing upright. After acclimating the fish for roughly 30 minutes, take the bag, turn it sideways, and allow the betta to swim out. Your betta may take some time to get used its new surroundings, but it should be comfortable living in the water of its new tank at this point.  If the water in the betta’s bag is dirty, minimize the amount that gets into the fish tank. Dirty water in your tank is never a good thing! After the fish has been acclimated, you can also take an aquarium net and gently place your betta in the tank. Do not feed your betta right away. The fish will probably not eat for the first day it’s in a new tank. Some bettas will refuse to eat for the first three days, sometimes even a week.

Summary in Indonesian:
Biarkan kantong plastik mengapung. Campurkan air tangki dengan air di dalam kantong plastik. Biarkan selama 15 menit. Lepaskan ikan cupang ke dalam tangki.