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Kokos Goldfish Forum Guidelines for Healthy Goldfish


shakaho

Guidelines are recommendations by experienced goldfish keepers for those of lesser (or no) experience. They are not the only way of keeping goldfish, or even the best, but are our compromise between ideal conditions for goldfish and the space, time, and money limitations of the goldfish hobbyist. Koko’s guidelines are continually reviewed and updated as needed by the moderating team as we gain new information from research and experience.

Tank

Optimally, your tank should be large enough to provide at least 20 gallons for each goldfish, with a minimum of 15 gallons per fish. This is true for both long-bodied and fancy goldfish. While baby goldfish can do well in a smaller tank short term, they grow very fast, so we recommend starting them in their grown-up tank.

The ideal tank for goldfish is shallow with a large surface area. Tall tanks should be avoided if possible.

Filters

The most common filters for goldfish tanks are HOBs (hang on the back) or canisters. We recommend a HOB filter be rated by the manufacturer as turning over at least 10 times the tank volume per hour. Thus a HOB filter for a 20 gallon tank should turn over at least 200 gph. If one has multiple HOBs the turnover rates should add up to at least 10x the tank volume per hour.

Canisters have more filter volume, and we recommend they turn over at least 5-7 times the tank volume per hour.

There are many other types of filters, including many DIY filters. If you are using any of these, please start a thread in the Water Quality forum to ask if your particular filter is appropriate for your set up and your fish load.

Water Changes

We recommend a minimum of a 50% water change each week. This assumes that you are meeting the recommendations for tank size and filtration.

Aeration

Aeration is not usually needed if your tank and filter(s) are large enough for your fish load, the water surface area is large enough to provide good gas exchange, and the fish are healthy. Even then, adding aeration is generally beneficial. We will often recommend adding aeration when treating sick fish.

Heaters

Goldfish are called “cold water” fish, not because they require cold water, but because they do not require heated tanks like tropicals. Generally, healthy goldfish prefer the same temperatures as we do and are happy at room temperature (including a cooler night temperature). However, we may recommend heating the tank when treating sick fish, so it is useful to have a heater available.

Substrate

Goldfish tanks may have no substrate, sand, or gravel. We recommend that hospital and quarantine tanks have no substrate for ease and completeness of cleaning. If one uses sand or gravel in the main tank, the layer should be no more than ½ inch thick. Gravel should be either small enough that the fish can easily swallow it or too large to fit in the fish's mouth.

Ornaments

Avoid hollow ornaments. The water in these can become anaerobic and produce toxins. Avoid ornaments that have sharp points or spaces that can trap a goldfish.

Salt

We do not recommend routine use of salt in a goldfish tank. Salt is a valuable, gentle medication which will lose some of its value if it is in the water on a regular basis.

Quarantine

We recommend quarantining all new fish for at least a month before introducing them to the “old” fish. During this quarantine period, we treat with salt and praziquantel.

Tank mates

Goldfish do best with other goldfish as their tank mates. Most other fish are likely to harm and/or be harmed by goldfish. Please ask about their suitability before adding any other kind of fish to your tank. Even fish that get on well in a goldfish tank, such as bristle nose or rubber lip plecos, or even large snails, produce waste. So adding these reduces the number of goldfish your tank can support.

Here are some articles with additional information about keeping goldfish.

http://www.kokosgoldfish.com/tensteps.html

http://www.kokosgoldfish.com/BRIEFGUIDEFORNEWOWNERS.html

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Thanks for this--this is great info and I wish I could have had access to it when I first got my goldfish instead of reading through a bunch of misinformation on other sites.

 

The only thing I was wondering is why you don't make a distinction between single-tailed and fancies. I was under the impression that single-tailed fish grow much bigger and need much more space, so a 40 gallon tank is probably not going to be sufficient for one full-grown common, much less two. Is this correct? The reason I ask is because I feel like a lot of beginners (like me a year and a half ago) actually have comets from feeder tanks and don't realize that the little 1/2" fish can grow to over a foot long and, as a full-grown adult, needs a 50+ gallon tank or a pond. 

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Thanks for this--this is great info and I wish I could have had access to it when I first got my goldfish instead of reading through a bunch of misinformation on other sites.

 

The only thing I was wondering is why you don't make a distinction between single-tailed and fancies. I was under the impression that single-tailed fish grow much bigger and need much more space, so a 40 gallon tank is probably not going to be sufficient for one full-grown common, much less two. Is this correct? The reason I ask is because I feel like a lot of beginners (like me a year and a half ago) actually have comets from feeder tanks and don't realize that the little 1/2" fish can grow to over a foot long and, as a full-grown adult, needs a 50+ gallon tank or a pond.

Short answer, a single tail is long and skinny, a fancy is short and fat. Same size. However, some fancies can get long and fat, and as such, are actually bigger! Think about people... A man can be 6'8 and 220 pounds or 5'10 and 300 pounds. Who is bigger?

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Thanks for this--this is great info and I wish I could have had access to it when I first got my goldfish instead of reading through a bunch of misinformation on other sites.

 

The only thing I was wondering is why you don't make a distinction between single-tailed and fancies. I was under the impression that single-tailed fish grow much bigger and need much more space, so a 40 gallon tank is probably not going to be sufficient for one full-grown common, much less two. Is this correct? The reason I ask is because I feel like a lot of beginners (like me a year and a half ago) actually have comets from feeder tanks and don't realize that the little 1/2" fish can grow to over a foot long and, as a full-grown adult, needs a 50+ gallon tank or a pond.

Short answer, a single tail is long and skinny, a fancy is short and fat. Same size. However, some fancies can get long and fat, and as such, are actually bigger! Think about people... A man can be 6'8 and 220 pounds or 5'10 and 300 pounds. Who is bigger?

 

Yep, For example, Bruce from TungHoi aquarium is the biggest goldfish in the record books for 2013 at 15" long, and is an Oranda. :) He would likely weigh the same, if not more than the world's longest goldfish, who is 18.5".

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Wow! This is so different from what I've read and been told--I keep learning new things. So I guess that's why 20 gallons per fish is the minimum, since some fish, whether single-tailed or fancy, will actually grow really big and need much more space? Thanks for clarifying!

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Actually, few fish grown in an aquarium are going to get too large for 20 gallons apiece.  Even for ponds, a recommendation of 20 gallons per goldfish is considered very strict. Most go for 10 gallons per fish. You will find some who say you should have 50, 100, or 130 gallons per pond goldfish. I can tell you quite confidently that these people haven't kept pond goldfish. While you can certainly stock a pond at any of those levels, you can only maintain those very low stocking levels (assuming you are providing good care) if: You also include predator fish that will eat goldfish youngsters that their parents missed as eggs/tiny fry; You keep ponds with only all males or all females; or You seine out all the fish every year and discard the extras.  The simple fact is the higher the stocking level of adult fish, the fewer fry survive, and the lower the stocking level of adult fish (assuming some of each sex) the more fry will survive. In my experience, 20 gallons per fish in the pond is a stocking level that is pretty stable.

Edited by shakaho

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I am a new member, and I think all that information, summarised in one spot is brilliant!  Thanks again the Kokos' team!  :thumbup2:

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I'm curious why 1/2 inch or less sand is recommended? Is that not including heavily planted tanks since a lot of plants need deeper substrate for their roots?

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This is to avoid anaerobic pockets.   It does not include heavily planted tanks with healthy plants.  The plant roots will aerate the substrate.  

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Actually, few fish grown in an aquarium are going to get too large for 20 gallons apiece.  Even for ponds, a recommendation of 20 gallons per goldfish is considered very strict. Most go for 10 gallons per fish. You will find some who say you should have 50, 100, or 130 gallons per pond goldfish. I can tell you quite confidently that these people haven't kept pond goldfish. While you can certainly stock a pond at any of those levels, you can only maintain those very low stocking levels (assuming you are providing good care) if: You also include predator fish that will eat goldfish youngsters that their parents missed as eggs/tiny fry; You keep ponds with only all males or all females; or You seine out all the fish every year and discard the extras.  The simple fact is the higher the stocking level of adult fish, the fewer fry survive, and the lower the stocking level of adult fish (assuming some of each sex) the more fry will survive. In my experience, 20 gallons per fish in the pond is a stocking level that is pretty stable.

There's something beautiful about the fact that there seems to be a stocking level that allows pond fish room to do their fish things that also happens to help keep the number stable so the fish aren't getting too cramped.

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One way I have kept my pond fish population at the level i want, which is about 50 gallons per fish, is to throw in a bluegill. No new fish since I did that. More gallons per fish means less maintenance for me. I could not imagine having 80 goldfish in my pond. I'm not willing to change 1000 gallons of water a week!

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This is very helpful information. Thank you so much! I wish I found this site from the beginning of my ownership of my sweet little babies. I hope as a new fancy goldfish parent now that my tank has cycled. I’ll now be able to perform a 50% water change each week. I have five goldies that are 2 1/2" - 2" body length. They were an inch when I purchased them 4 months ago. However, since I have five goldies. It's time go shopping for a larger tank. Being that I have them in a 55 gallon, 4 ft length tank. I want them to live a long and happy life. They are so much fun to watch and interact with. Who knew goldfish could be so smart?

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What i tell people in a nutshell:

 

  1. 25-30 gallons per fish at the least.
  2. Keep decorations to a minimum, especially straight edged or pointy decorations.
  3. Keep a thin layer of gravel. employ snails to break down mulm and algae. if you can stomach them. once they are in your tank, they ain't coming out :)
  4. Don't over feed.
  5. Over filter and manage flow
  6. Do your water changes. lots of them.

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That's good advice, but please observe, "Guidelines ...are our compromise between ideal conditions for goldfish and the space, time, and money limitations of the goldfish hobbyist."

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That's good advice, but please observe, "Guidelines ...are our compromise between ideal conditions for goldfish and the space, time, and money limitations of the goldfish hobbyist."

 

Excellent feedback. Agreed.

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ok what about some people saying you can do 20 gallons for the fist fish and 10 for any fish after that i have been following for a while now and hove seen no adverse affects but i do larger water changes so that may be why.

Sent from my SM-G928T using Tapatalk

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Does it make sense to you that a single fish needs 20 gallons of water, but with a tankmate, the same fish needs only 15 gallons, and give him 9 tankmates and he only needs 11 gallons? I assume whoever dreamed up this silly rule thought that a goldfish needed only 10 gallons of water, but looked at a adult goldfish in a 10 gallon tank and saw that the fish clearly needed more room.

You have correctly observed that increasing the frequency and/or the volume of water changes allows you to safely keep more fish in the same amount of water.

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1 minute ago, shakaho said:

Does it make sense to you that a single fish needs 20 gallons of water, but with a tankmate, the same fish needs only 15 gallons, and give him 9 tankmates and he only needs 11 gallons? I assume whoever dreamed up this silly rule thought that a goldfish needed only 10 gallons of water, but looked at a adult goldfish in a 10 gallon tank and saw that the fish clearly needed more room.

You have correctly observed that increasing the frequency and/or the volume of water changes allows you to safely keep more fish in the same amount of water.

This was a thing years and years ago when Goldfish sites line mine where just starting out and we are where trying to get the information out there. No harm just old information :) We all know better now :) 

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