You should never completely clean the tank.
Do 25% weekly water changes.
Also add some live plants so they can absorb ammonia,nitrite, and nitrate.
You don't need to take out the fish. Just keep him in their while cleaning.How to change water in an aquarium?
You do 25% water changes every single week, and you do it with a syphon hose vacuum, so you can vacuum the gravel and drain the water at the same time. You'll need a bucket to drain old water into, and a bucket to prepare the new water. syphon vacuums are sold at any pet store. It won't harm anything to skip a week here and there, but keeping up the weekly routine will keep your fish healthy. You can do half twice per month, but every week is better for the fish.
Keep in mind those two goldfish can grow very large and are not suitable for tiny tanks. If your tank is less then 20 gallons, I will strongly encourage you to take them back and look into fish that don't grow too big - white cloud minnows are great for small and unheated tanks and you can have a bunch of them.
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A huge water change can be done safely if you are in a bind, but water right out of the tap can easily be oxygen deprived, and the ph can change quite a bit as the water settles and aerates. Done wrong, a very large water change can kill a tank of fish. Less is safer.How to change water in an aquarium?
Put it in a bowl/tank of water which has benn left for a few days to get to room temperaure and put them in that whilst you clean them out and put them back in their normal tank a few days later!How to change water in an aquarium?
In the great majority of cases, you don't need to remove the fish from the tank to do a water change. Just take out 50% of the water, and fill the tank again with new water with the right amount of dechlorinator for the water you're adding.
If you can %26quot;vacuum%26quot; the gravel with a gravel cleaner siphon, that's even better, but the most important thing by far is the water change.
You can do all this with the fish still in the tank.
Some people will tell you not to make too large a water change at once. This was the current thinking in the hobby about 50 years ago, but it was mistaken. A large water change will not shock the fish, as long as there is no great temperature difference between the old water and the new water. What stresses fish, often fatally, is living in dirty water. If you only change 10% or 20% of the water at once, you are leaving 90% or 80% of the pollutants in the tank. I normally make 50% water changes, but the truth is that larger changes (75 or 80 per cent) are also acceptable, as long as the new water is close to the temperature of the old water.How to change water in an aquarium?
Just siphon off the 25% preferably using a graves cleaner and refill with aged water if possible or treat the water. if you will use tap water do a smaller amount. You did not say if it was a tank or bowl. If it is a bowl keep a bucket with enough water for a 100% change and put the fish in another container while doing it. Be careful netting it the bubble eye is prone to damage. When I had them I caught them with my hand after wetting it well.How to change water in an aquarium?
NEVER, I repeat, NEVER change 100% of the water, because the fish will think that it is in a different place. Changing 25% of the water is good, one a week or two.
Once a month or two, empty half of the water and clean the bowl from inside with ONLY WATER!
