Monday, February 23, 2009

Goldfish: Caring for them & some common myths

First, let's look at some goldfish myths and the real truth.

"Goldfish will only grow as big as the tank lets them. They are perfectly happy in bowls because they don't grow too big."

On the outside, it appears that the goldfish does only grow as big as the tank allows. However, goldfish do not have an automatic growth controller that clicks off when the goldfish can't get any larger without having much swim room. A goldfish's natural size varies from 8 inches for the fancy breeds to over 12 inches for the comet. If a goldfish is kept in a tiny tank or bowl, it is stunted. But only on the outside. Its organs keep growing and growing until the outgrow the body, which leads us to our next myth:

"Goldfish only live for a few years."

Sadly, most goldfish do live for only a few years due to improper care. If kept in a proper environment, a goldfish's natural lifespan is 20 years or more. The oldest goldfish on record lived to be 49.

"Goldfish do not need a filter. They are very hardy and are fine without one."

Goldfish do need a filter, much more than most other fish. They are extremely messy. Unless it is removed some way, the waste and excess food rots, which will kill the goldfish because rotting waste and food produce ammonia. Ammonia burns a fish's gills, which leads to a painful death if the situation is not addressed quickly. Even then, a fish can have lasting damage to the gills.

Now, let's talk about setting up a goldfish tank. Goldfish need much larger tanks than other common fish because of their adult size. If you take good care of your goldfish, it can be with you for over 20 years!

The general rule of thumb for goldfish is 20 gallons for the first goldfish and 10 gallons for each additional goldfish. Goldfish need excellent filtration to keep all of the waste down. Buying a filter for a goldfish can be more expensive than for another kind of fish, but since goldfish do not need heaters, the cost is probably about even. List of things to buy:

29 gallon tank
Filter rated for a 40-60 gallon tank
Plants (Live plants look nicer, but a goldfish will uproot them and possibly eat them)
Optional decorations/accessories (like caves, statues, driftwood, etc.)
API master test kit (if you don't already have one)

You probably won't want to only have one, so let's say you're wanting to start out with 2. You'll need to buy a 29 or 30 gallon tank. The difference between them is that a 29 gallon is 30 inches long, while a 30 gallon 36 inches long. 29 gallons are probably more common than 30's.

Do not buy a goldfish yet!!!! If you add your goldfish right now, they will die of ammonia poisoning because your tank has not completed the nitrogen cycle. Look here for detailed directions. I would recommend using the "Add Daily" method, even though it takes longer, because in the end there will be much more beneficial bacteria to eat up your goldfish waste and the fish will be much less likely to die.

After you have cycled your tank (your tank has 0 ammonia, 0 nitrItes, and 10-20 nitrAtes), you can add, at most, 2 goldfish. If you are using a 29 or 30 gallon tank, you need to get one of the fancy varieties, like a Black Moor or a Fantail and NOT one of the longer plain varieties, like a Comet, because these grow much larger. Here is an example of how big the fancy varieties can get if kept in healthy conditions. This kind of growth is NORMAL! Pond goldfish are not the only ones who naturally grow large.

Make sure you do a 25-40% water change once a week to keep your fish healthy. NEVER totally empty the tank and wash the gravel, because this kills the ammonia-eating bacteria!


Jen said...

very informative blog, Maddie! I didn't know many of those things and was thinking about getting some goldfish for my pond. Is there anything else I should know if I want to put them in an outdoor pond?

MaddieLynn said...

Jen -

The pond needs to be at least 4 feet deep to keep the temperature stable. In the winter, if it gets very cold, you may have to bring them inside. Comet goldfish are probably better for a pond than the fancy kind becasue they are hardier. Make sure you are getting goldfish and not koi - koi can look like a goldfish when they are small, but they grow to be 3 feet or more and need at least a 1,000 gallon pond.

MaddieLynn said...

Here's a link about pond goldfish:

Leachy903 said...

wow verry good fish blog, i am planning to get some coldwater fish, and i really wanted a fantailgoldfish in a 30-45 gallon tank, but im wondering, will they get too big, or will it be un healthy? also how do i get rid of there waste?