The 5 Most Basic Goldfish Info – Let’s get it rolling

There is a vast amount of goldfish information out there and what I am sharing here are only a few to kick start the hobby.

These are the 5 most basic goldfish information that we should take into consideration when planning for our goldfish keeping.

Picture of goldfish

1. They can grow very big
Yes… you will usually see those small and cute ones in your local fish stores (LFS) and thought that those are the sizes they will stay in. Nope! I have seen some from my LFS here and they are bigger than both my palms side by side.

So how big can goldfish grow? Well apparently the flat bodied common goldfish can go more than 12 inches. The round bodied fancy ones are smaller at an average of around 6-8 inches. Anyhow, I guess it’s most goldfish keepers’ dream to see their fish thrive and grow big.

So what’s it to you?
Assuming you want to continue keeping them alive, you will need to consider giving them a big environment to live & grow. The common guideline is 20 gallons of water for the first fish, and 10 gallons each for the subsequent ones.

2. They eat and poop a lot
I have heard that goldfish will eat and eat and eat until their stomach explode. I am not sure how true is that but I do know they eat a lot. They will eat any food that fits into their mouths including small fishes. I have witnessed my goldfish gobbling up an Otocinclus (a type of small algae eating fish) in my tank before!

With eating a lot, comes pooping a lot. It’s funny seeing them swimming around with a long string of poop sticking out their backside, kinda remind me of a rhythmic gymnast with ribbon.

So what’s it to you?
You may want to reconsider if you intend to keep goldfish with small fishes.
More poop will mean more maintenance needed to keep the water in good condition.

Picture of Oranda

3. They are freshwater fish
Goldfish are freshwater fish. If you are thinking of putting a goldfish to keep your Nemo or your Dory company, DON’T. Nemo & Dory are saltwater fish. Goldfish will not thrive in saltwater.

So what’s it to you?
If you set up the wrong type of water for your goldfish, you will end up with a dead salted fish instead.

4. They like cold water
Goldfish prefer water temperature between 18-24°C. They do have high tolerance to different temperature though. I live in a tropical country & my tank’s water temperature is slightly higher than 24°C. So far my goldfish are doing well.

So what’s it to you?
If you are from a country with many seasons (oh how I envy you!), you’ll need to make sure your tank’s water temperature doesn’t fluctuate too far away from the range mentioned above.

Picture of Veiltail

5. They come in many varieties
Due to generations of selective breeding, goldfish come in many varieties. Some of them  are Comet, Oranda, Telescope, Bubble Eye, Celestial Eye, Fantail, Lionhead, Pearl Scale, Pompom, Ryukin, Shubunkin, Ranchu, Veiltail, Butterfly Tail, etc.  Each of these varieties have distinct features about them. In terms of body wise, some have flat long bodies which allow them to swim fast while some have rounded bodies which allow them to look cute but slow swimming.

So what’s it to you?
Although generally they all have the same requirements, knowing their distinct features & behaviors will help you to plan your goldfish keeping accordingly. For an example, the food may all be eaten by the fast swimmers before the slow swimmers could get to them, if they are being kept together.

So there you go, 5 goldfish information to get the ball rolling.

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16 Replies to “The 5 Most Basic Goldfish Info – Let’s get it rolling

  1. Thank you so much for this very in-depth and informative article on goldfish. I had no idea there were so many types and the fact that they grow quite large. I think it’s because, I hate to say, that they die before they grow to be that big.

    You mention that gold fish can tolerate temperature changes. Can you put a goldfish into a freshwater tropical tank?

    1. Hi B.A.Scott,

      Thank you so much for your comments. It’s so true that most of the time our goldfish die on us before they really grow to their max. Hopefully with better understanding of goldfish and how to provide proper care, they can live a longer and healthy lives.

      Although goldfish prefer colder water, they can be kept in freshwater tropical tank as well. I am from a tropical country and my goldfish are doing fine. However if you are keeping them with other tropical fish, you may want to be careful that they can get along. Tropical fish such as the barbs have the bad reputation of nipping on goldfish fins.

  2. Thank you some great tips here. I’m thinking about buying some goldfish for my daughter who really wants them, but I’m worried about the maintenance side of it.

    Please could you tell me how often do you have to clean the tank out? Is it every week?

    Also, do you need to have the air bubbles machine in their (sorry I don’t know the proper name for it) to oxygenate the water? Thank you for your help.

    1. Hi Simon,
      Thanks for the comments.

      Goldfish are really beautiful, but I have to say that they are really messy as well.. so yes, there will need to be frequent maintenance. How often will depend on how many fish you have, how big is your fish tank (or any environment that you are keeping them in) and how good is your filtration system.

      In my case, I have 5 goldfish in a 3 feet tank (~ 48 gallons) and I do tank maintenance such as partial water change, cleaning the glass etc once a week. If you have a very small tank with basic setup, you may need to do maintenance more often depending on the water condition.

      So typically to set up a goldfish tank, these are the most basic things you will need for a start:
      – a tank or a container. The bigger the better. Note that the common guideline in fish stocking is 20 gallons for the first goldfish, another 10 gallon each for subsequent ones.. and i know I am not strictly adhering to this for my tank. 😉
      – an air pump to aerate the water
      – a filter (the most basic one is the sponge filter)
      – substrate such as sand (optional)
      – decorations (optional)

      If you decide to go ahead with keeping goldfish, please do read my following post:

  3. Nice, informative read.

    I’ll be honest, I knew nothing about goldfish before reading this. I thought they were all just that stereotypical small fish you get as a prize somewhere. If I were to have seen one that was as large as both my palms, I wouldn’t have known it was a goldfish.

    If I were to have some goldfish, now I have the insight to not accidentally kill it immediately lol

    1. Hi Enrique,
      Thanks for the visit. Goldfish do come in many varieties (and price ranges). They all have the potential to grow very big i.e 5 inches to 1 feet depending on which type. It’s just that most of the time, they died on us before reaching those size. Hopefully with better understanding and care, we can see them grow to their maximum potential.

  4. Hi, I had no idea there were so many different types of goldfish! Very interesting post. I have thought of getting fish a few times but I never have because I’m too sensitive and, well, fish die. I tend to keep pets with longer lifespans just for that reason, but maybe I will give goldfish a try!
    I especially like the part where you said the fish swimming around with long strings of poop trailing behind them reminds you of rhythmic gymnasts with ribbons. Haha!
    Thanks for the info!

    1. Hi Briana,
      Thank you for dropping by. I remember when I first got into fish keeping, a senior told me that there’s one ultimate rule to fish keeping that I must remember. The rule is “Fish die”.
      So the point of the hobby is for you to continue learning on how to keep them alive and how to take care of them properly. 🙂

  5. Thanks for the information. You are really an expert on gold fish. You even know what is the optimum temperature of breeding gold fish. I learn a lot from reading your post.


    1. Thanks Jay for your comments. I have been passionate about keeping goldfish for a while now, and I love to learn and share my knowledge about them.

  6. I haven’t had goldfish for years! It’s funny you mention how big they get, just a month ago I was at a friend’s house and they had two goldfish that were nearly as long as my hand. I had no clue they were goldfish until I asked, as I always thought they were small.

    I’ve heard that goldfish have a 5 second memory. When I used to have them, I swear they knew they were going to get fed when they saw me grabbing the fish food container from where I kept it near their tank. They’d start swimming around all excited! Maybe I was just imagining it! What are your thoughts on their memory? Do you think they recognise their owners?!

    1. Hi Angela,
      I bet your friend must be really proud of their goldfish. I think as goldfish keepers, nothing delights us more than to have our goldfish healthy, happy and growing.

      As for the 5 seconds memory, I think that’s just a myth. I have similar experience like yours where my goldfish know when it’s feeding time. I have seen a documentary on a study done on this as well where they put a goldfish in a maze. That goldfish was able to learn, remember and navigate the maze to get to the food.

      I am not sure about recognizing the owner part. I think when they know it’s meal time and a figure comes near to the tank, they will relate that to food.

  7. Hello and thanks for sharing, your post brings back my childhood days when I had so many goldfish. I also liked to go by the pet supply store and watched them swim. Goldfish are so colorful and very beautiful and have also seen some very big ones before.
    Your post on goldfish is pretty amazing.

    1. Hi Norman,
      Thanks for your comments. Goldfish are indeed very colorful and beautiful, and they come in many varieties.

  8. Hey there! My little sister’s birthday is coming soon and I notice that she likes fish especially goldfish. I don’t have any ideas about goldfish but I want to buy one for my sister. I found your article very informative and interesting to read. I’ll try to research more about different types of goldfish or let my little sister what’s her favorite goldfish. Thank you for sharing this information.

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