Rambling on goldfish

Goldfish get to a very large adult size and need a lot of oxygen. It is recommended that as large a container as possible be used. Its true that a 40-liter aquarium can house two to four small goldfish for a while but they will not reach their full growth potential or be as healthy as they could be.

To properly house goldfish, they (all types) need 75 square centimeters of surface area for every 2 centimeters of goldfish. That means 120 to 200 liters of water for every goldfish. Ponds make the perfect homes for goldfish. Remember fancy goldfish are slower moving than the single tail varieties and should not be housed together. These are also cold water fish, so they should not be housed with tropical fish.

I kept six beautiful goldfish in a 1 meter by 2 meter pond. This pond was constructed out of wood (2x4s). The inside sides of the pond were lined with good one-sided plywood. The floor inside this frame was lined with Styrofoam. For draining this pond, a two centimeter deep well (about 15 centimeters wide) was left at one end. Then a pond liner was nailed to the top of the wooden frame. The outside and top of the frame was covered in wallboard to match the wall. This is an 800-liter pond. This allowed just over 120 liters of water for each goldfish that I housed in there. A pond pump with a filter box was used. This pump had a bubble fountain attached to it to keep the surface water gently moving. One has to be careful with the fancier goldfish as they can not take a strong water flow into the filter or any strong current caused by the filter.

I also have used kiddy pools to house some of my goldfish. These pools were larger than the homemade pond. I kept some ryukins, black moors, and orandas in them. On one of the kiddy pools a large inside canister filter was used along with a large outside box filter, and were stocked with water lilies and other pond plants.

Water changes were done about once a week. Because goldfish are cold water fish all we had to do was dump some water (outside) and refill with the hose from the outside tap. Of course, caution must be taken to ensure that the water being put into the pond is approximately the same temperature. With these conditions provided, my goldfish grew, matured, and spawned on a regular basis.

I have housed two orandas in a 100-liter aquarium serviced by an outside canister filter with a sponge on the intake tube so that these clumsy fish didn’t get pulled in. This was a bare aquarium, as goldfish have delicate fins and features that can be easily damaged.

Other smaller containers can be used for quarantine and temporary housing. The idea here is to not leave them in to cramped of quarters for too long a period. Remember that surface area is most important. So a low shallow container with a large surface area is much better than a goldfish bowl with a very small opening in the top. The tall skinny ornamental tanks are simply not suitable for goldfish. Also remember that some of these fancy goldfish are best viewed from the top.

Yes, I have actually used a cat litter pan to quarantine a bubble-eye goldfish for a short while. The litter pan met the requirements of having a large surface area for oxygen exchange, even though it was quite shallow.

I have heard all sorts of people say that they wouldn’t keep goldfish because they are dirty fish. First of all, what does that mean? I take that to mean they put five fancy goldfish in a 40-liter tank, over fed, didn’t do any water changes, and ended up with a dirty tank. I would say that could make these fish dirty fish. In my experience if the above mentioned is avoided there shouldn’t be a problem. My pond, pools, aquaria, and substitute containers are always crystal clear.

Ideal water conditions for goldfish are a pH of 6.8 to 7.6 and a temperature of 68 to 76 degrees They can live with a pH as high as 8.2 and a temperature as high as 90 degree as long as the water is well aerated. They prefer moderately hard water but can live in very soft to very hard water. Ammonia poisoning is especially harmful to goldfish, the first signs being blood streaks in their fins. I kept my goldfish in a pH of 7.5 in soft water with no problems.There is an adage in goldfish keeping that says that the key to healthy fish can be found in water quality. It is repeated so often that people take this saying for granted, or perhaps lose sight of what it really means. There are several important elements to water quality, including: maintaining consistent water parameters; maintaining adequate stocking levels; and installing effective filtration systems. Every fish keeper should look toward maintaining consistent water quality parameters. The first thing to keep in mind is that the rules for fish length/ water volume were originally designed for tropical fish keeping. Fish length measurements between tropical fish and goldfish just won’t work. Most goldfish have several times the mass of similar-sized tropical fish. Water volume and filtration requirements won’t work for goldfish due to their increased mass when compared to tropical fish.When designing a filtration system for goldfish, keep in mind their increased metabolic requirements. This means that you will likely have to over-spec both biological and mechanical filtration for a goldfish aquarium. Similarly, when determining water volume requirements, err of the high side with goldfish; in other words, always plan to provide a larger volume of water than you originally estimated. Most successful goldfish breeders and show participants have stocking levels of 3 – 4 fish (5 inches and over) in a 55 gallon aquarium. While this might seem too restrictive, consider that you should not be aiming at having your fish survive, but thrive.

Goldfish will eat almost any kind of food being fed. Pellets are a very common diet for goldfish. Any commercial brand is fine. I fed a variety of small pellets including wheat germ pellets for goldfish. I do not feed the larger sizes of pellets as they can also cause swim bladder problems. My outdoor fish also get earthworms, assorted bugs, and mosquito larvae. On the very odd occasion they may even have gotten frozen bloodworms.

When visiting a fellow hobbyist’s house, I was oooing and ahhing over her beautiful goldfish. Then a very nice red and white fish caught my eye. She began to laugh at me because the approximately 40-centimeter fish was a 10-cent feeder fish that she had bought to seed her pond with. This was a very nice single-tailed goldfish that had brighter coloring than her fancy goldfish.

Goldfish can be very beautiful if the proper conditions are provided. Lots of room lots of water changes (especially if kept in smaller containers), cooler temperatures (no heater needed as long as temperatures don’t drop below freezing), and lots of oxygen (air exchange). The hobbyist will find that goldfish are not any dirtier than any other fish. These fish are more challenging than tropical fish. One more thing I have to add here, goldfish are truly not a fish for children. I have been told many times in stores that they don’t need to carry quality goldfish because they are meant for children to keep in goldfish bowls, and it just really didn’t matter. It makes you wonder how as a breeder that specialized in quality goldfish I have survived for over 20 years just selling goldfish to the children. I wonder how many four-year-olds buy $300 goldfish?????


Rick