Red wag platy

I know everyone here knows the myth that a goldfish will only grow as large as its enclosure, or something like that. I know this myth is explained somewhere, but i can't seem to find where. Can someone please explain this myth to me and what determines how big goldfish grow. Does bad water quality affect it? Thanks.

Shawnie

Worried parent of 2 gorgeous goldfish see if this gives ya any more info

gremlin

A goldfish will grow to the depth of its container. That doesn't mean it will be happy. Your comet appears to be a beautiful male. Some of mine will come up and take food right out of my fingers. They definitely know who feeds them and when that person walks by...

Shawnie

IMO fish will grow no matter what their container is..if theres no more room, they will die...it doesnt mean they will stop growing just because they are in a small tank

Red wag platy

Thanks shawnie, but this didn't really answer my question. What I'm wondering is what determines how big a goldfish will grow? I've seen goldfish that have stopped growing at three inches and ones that have grown to 6 inches. Is it favorable conditions?

sirdarksol

Like with humans, a variety of factors will influence the size a goldfish grows to.

Goldfish will continue growing throughout their long life, though this growth slows at a certain point.
A healthy goldfish will grow quicker. The biggest influence on this is the nitrate level in the surrounding water. This is why goldfish will seem to stop growing in a small bowl. They haven't stopped, but their growth has been severely stunted in the same way that a human child exposed to large amounts of toxins will likely have stunted growth. There is also the belief that certain organs may continue to grow, eventually leading to a painful death as the organs crush each other.
Note that mental stress will likely make the goldfish less healthy. Goldfish are smart enough that they need a bigger tank, even if the water quality is somehow kept pristine. They will stress out if kept in a little 10g tank.
Genetics play a part, too. Some of the fancier goldfish have a slower growth rate than the comets. Like in humans, different specimens from the same line will have different growth rates.

I have a goldfish whose growth had stalled out. He was living in a little 20g tank (the previous owner of the tank didn't know anything about keeping fish, and neither did I when I adopted the tank) with numerous other tankmates. He is currently in a 30g tank with a koi, and has almost doubled in size since the move. The two will soon be moving to a 200g tank which will likely be their permanent home (unless either the walnut tree or the pine tree comes down in my back yard, in which case I'll have space for a pond). I expect that he will continue to grow for the next twenty or so years, and I'll have a darn huge goldfish by the end of that time.

gremlin

the depth of the water is a factor also. My pond and my sister's pond are about the same size length and width. her pond is twice as deep as mine. Mine has a better filter system on it. Both of us started out with fish less than 3 inches long. her fish grew to be about 1/3 bigger than mine. I agree that there are a lot of different factors that can affect their growth, but at least with the basic 'feeder' comet goldfish, depth of the water does play a part in how fast/big they grow.
Koi, on the other hand, continue to grow no matter what depth their tank/pond is.

sirdarksol

I have seen no such information on this. In fact, the information I have found contradicts any concept that the size of a body of water directly affects goldfish growth. There is no mechanism in the goldfish's physiology that restricts the creature's growth.
I would bet very strongly on some other factor being involved, perhaps even being indirectly related to water depth, such as exposure to sunlight, types/amount of micro-organisms growing in the pond, the previously mentioned depression, etc...