Watch the video below on how to set up a sample quarantine tank for saltwater fish and how to medicate the fish if necessary.
I got him two guppies and two gold fish. But the gold fish died two days after I put them into the tank. I did some research online, and people said I have to change the water to keep it clean and maintain enough oxygen. I usually put some tap water in another tank, and keep it for 3 days, and every time I change half of the old water I clean the tank thoroughly. But every time after I change the water, it becomes dirty again soon after, and the fish swim on the top slowly, just like they're lacking oxygen.
First of all, I didn't have any experience on fish keeping before. But my child really wanted to have some fish, so I bought a small (0.5 gallon) fish tank.
Can you use an old reptile tank for fish? - Petco Community - 493
Aquarium Filters for Fish Tanks | That Fish Place - That Pet Place
For freshwater fish you may be able to get by without having a quarantine tank. Freshwater fish are generally more suited to captivity because they are usually tank raised and don't seem to break out in disease as readily as their saltwater counterparts. However, if newly acquired fish do come down with something such as ich (ick) or velvet, you will surely wish that you had one ready to go. One newly bought fish that is introduced to your main tank can easily wipe out the entire tank population. Better safe than sorry, right?You don't need to go all out here. A simple tank size of 10 - 20 gallons will suffice for most people. If you have larger fish, then obviously you want to get a bigger quarantine tank. All you really need is a bare bones setup with the following equipment:For keepers, I would say that you definitely need a quarantine tank (sometimes called a hospital tank). Marine specimens are mostly wild caught and not used to being kept in captivity. Their journey to a dealers tank is usually much longer and much more stressful for them. Stressed out fish will usually come down with some kind of disease if they don't simply die from the whole ordeal. Saltwater fish keepers will usually have other things in the main display tank such as invertebrates and , that they don't want to expose to the harsh medicines necessary to treat one or two fish. Some medicines can wipe out all of the invertebrates in a tank, so be sure to research any medicine before using it in your tank.If a fish comes down with something while in your main tank, just net them and put them into the quarantine tank. There should be no need to acclimate them because you used water from your main tank. If you didn't use water from the main tank you will need to acclimate them to the quarantine tank water. Diagnose the problem / disease and treat appropriately. After the disease clears up you will still want to keep the fish in quarantine for a week or so monitoring the water parameters with your test kits the whole time.