It is my absolute #1 pet peeve when I see goldfish in 'goldfish bowls'. Here are basic facts that many people are absolutely amazed at hearing.

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Goldfish are a small type of koi that grow to be 12 inches (30cm) long or larger.

Goldfish live up to 30 years if properly cared for.

Most goldfish die of growth stunts. 20 gallons (76 liters) is the smallest tank size you should consider housing one in. This means 20 gallons per goldfish. Large ponds are even better.

Goldfish are very messy, and strong filtration is absolutely necessary! Otherwise ammonia and nitrite levels sky-rocket overnight, burning your fishes skin and insides in no time, and killing them slowly (or quickly). Filtration is also necessary to oxygenate the water. Yes, fish need air too!

Recent studies have suggested that fish feel pain. Brain and nerve activity has been recorded that is very similar to human and animal activity while feeling pain. Google it.

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I don't mean to reduce anybody to tears, but remember little Goldy? That three centimeter long goldfish that lasted a month in that smelly little goldfish bowl?
Poor water quality either burned him to death, or he suffocated. And it probably hurt... ;_;

I did my fair share of fish killing, (all drains don't lead to the ocean...), but getting educated and changing your behavior is the best way to fix what has been done.

Goldfish are more than ornaments. My own baby Courage is going to be with me for a long time yet, and he's just as dear to me as a dog or a cat. You can even train them. Youtube it. :P

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Ooh-rah!

Just a little pointer though, Common goldfish should really have a 6 x 2 x 2ft tank or a pond (which is even better) if they are to reach their full size without suffering from the effects of stunted growth.

Not necessarily, recent studies have been met with a great deal of controversy. While fish may react to stimuli that we normally associate with pain, it has not been proven how the brain processes these stimuli into responses. It's still a rather moot point.

I've got comet goldfish in a pond and some other goldfish in a 20 gallon tank with a filter a very good filter too.

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Diesel curtesy of Tashi.

My babies.

6 tank fish. Dylan, Monty, Shadow, Ghost, Phantom, Sidney aka Sid for short

23 pond fish. Zoomie, Cash, Tod, Murphy, Bingo, Kovu, Rufus, Wilbur, Miles, Mitzy, Ralph, Stan, Archie, Marley, Megan, Tommy, Ike, Twix, Rio, Keesha, Oz, George, Bruce.

In my heat of ranting I did wrongly word that. Have reworded it to sound as I learned it, thanks for the pointer.

As for the tank size, 20 gallons is certainly not ideal, but to survive a fairly average lifespan (although not flourish), it is the minimum, I would argue.

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im planning to get a fancy goldfish in a week or 2, what is the minimum tank size it can live in? is it about 50L?

Goldfish can grow big I would recommend a 20 or 40 gallon tank with a filter.

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:
Diesel curtesy of Tashi.

My babies.

6 tank fish. Dylan, Monty, Shadow, Ghost, Phantom, Sidney aka Sid for short

23 pond fish. Zoomie, Cash, Tod, Murphy, Bingo, Kovu, Rufus, Wilbur, Miles, Mitzy, Ralph, Stan, Archie, Marley, Megan, Tommy, Ike, Twix, Rio, Keesha, Oz, George, Bruce.

75L is the minimum you should get, you might have to get something bigger later on. Get a strong filter. At least 4 weeks before you bring your fish home, set up the tank and just let it run for the four weeks. Invest in a book and test kit, etc. before you bring Goldy home, so you know what you're getting yourself into.

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Remember, the cycling process is a very important part of the aquarium's early days. Just leaving the filter for a few weeks won't really do much, you need to add a source of ammonia to give the fledgling bacteria colony something to feed on and multiply. Bottled household ammonia (7.5% concentration) would be ideal, and can be obtained from most drug stores and supermarkets in the cleaning aisle.

If you just leave the tank unattended for a few weeks, you'll have big problems with NTS (New Tank Syndrome) once you start adding fish, as the filter can't cope with the sudden increase in biological waste.

I was assuming that the books would have that, but what Chillinator said. ^^

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