spacer spacer spacer spacer spacer spacer spacer spacer spacer spacer spacer
Main Goldfish Information

Pic of the
WeekPic Of The Week

Cycle of the tank
Goldfish Care
Goldfish Food
Fry Food
Goldfish Plants
Goldfish Breeding
Goldfish Diseases
Goldfish Filtration
Ten Steps to
a Healthy Goldfish
Goldfish Changing Color
Gel Food Recipes
Types of Goldfish
Goldfish Books
Compatible Fish

Goldfish Forum

Goldfish Discussion
Goldfish Disease
Tanks & Equipment
Water problems?
Goldfish Food
Goldfish Breeding
Goldfish Photos
Goldfish Videos
Koko's Kritters
Research, Articles and Tips
Tip of the Month
Research Articles
Do It Yourself
Bruce The Giant Goldfish
Importance of Water Changes
Salt Bath
Salt as Treatment
Nitrites and Salt
Moving Goldfish
Steps To Building A Pond
Tank Repair
Onion Plant
Moss Balls
Live Plants vs Plastic
The Comet
The Lionhead
Black Moor
Bubble Eyes
Conversion Page
Goldfish Clubs
Koi and Goldfish Shows
Advertise Here,
Email for Details

Goldfish Care

Welcome to my general fish keeping page.
On this page you will find general information on keeping a goldfish health and happy.

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.


Your tank should be large enough to provide at least 20 gallons (76 liters) for each goldfish. 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. If you provide less than 20 gallons per adult fish, you should increase the amount of water changed to maintain water quality.

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


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 (76L) tank should turn over at least 200 gph (760 lph). 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.

We do not recommend internal filters for goldfish.

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. If (for example) you have one fish per 10 gallons (38L), you should do a minimum of two 50% changes per week.


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, (a minimum of 2 ft2 (1858 sq cm) per goldfish) and the fish are healthy. Even then, adding aeration is generally beneficial. We will often recommend adding aeration when treating sick fish.


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.


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


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.


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.


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.

© Copyright Koko's Goldfish 1999-2019. All Rights Reserved.

*Privacy Statement and Contact Information*

Site Map