Tank Mates for Goldfish: Learn Which Species Are and Aren't Compatible
Fish Compatible With Goldfish
Goldfish on their own kept properly require lots of space. Common goldfish, comets, and shubunkins cannot be kept with fancy goldfish. Additionally, some types of fancy goldfish such as orandas, black moors, and fantails shouldn’t be kept with other fancy types like ranchus. The reasoning behind this has mostly to do with the faster of the fish being able to eat all of the food before the slower, fancier varieties can get their needed share. Nipping can also be a factor, and something that fancier and slower goldfish are unable to avoid.
Telescope goldies probably should not be housed with any other kind of fish due to their fragile nature. You may try a couple of snails.
There are, however, other types of freshwater fish that may be successfully housed with most other goldfish, as long as proper, partial water changes are regularly performed. The two main reasons people defend the theory that no fish can be kept with goldfish are different water temperature needs and the high waste level of goldfish.
Goldfish are cold-water fish, requiring a steady temperature of somewhere between 65 and 75 degrees. Therefore goldfish are never compatible with any type of truly tropical fish, which of course require warm water temperatures. However, there are other cold-water fish, as well as subtropical fish, that do well with water temperatures in the sixties to low seventies.
Goldfish—no matter the variety—tend to produce a good deal of ammonia, which in a well balanced and cycled tank ultimately produces a good deal of nitrates. While not as harmful as nitrite or ammonia, nitrates are still toxic to fish, and partial water changes must be kept up with to keep nitrate levels low.
In a large enough environment that is well maintained, tank mates selectively chosen from the subtropical and coldwater species can be compatible with goldfish. There are a couple of other considerations, such as fin nipping, aggression, and other compatibility issues, that should also be considered when selecting potential tankmates.
Some fish not generally considered aggressive or fin nippers may still not interact well with goldfish, such as common plecos and possibly corydoras. There is a good bit of anecdotal evidence to suggest that common plecos will take to sucking the slime coat off of goldfish, leaving them at risk for infection. This is a serious problem for goldfish and should not be risked. Corydoras have been reported to do the same thing, though the anecdotal evidence is less abundant. Additionally, corydoras are sensitive to certain common goldfish medications, and would need to be removed from goldfish tanks anytime those medications are used. Because of these reasons, common plecos and corydoras, or any other type of normally aggressive fish should never be chosen as tank mates for goldfish.
The last thing to consider is that as goldfish grow larger, they will be able to eat many smaller fish. This is reported to be a much less likely occurrence if they were raised with the smaller fish and are therefore used to them and not likely to consider them as food. Nonetheless, there is nothing to prevent a mature goldfish from changing its mind.
With all of that in mind, some possible choices are listed below. While these species may be among the best tankmates for your goldfish, issues can arise in any tank that contains multiple species.
Weather Loaches, also known as Dojo loaches, are commonly recommended companions for goldfish, as they are coldwater fish themselves, requiring temperatures in the 60 to 75 degree range. However, they need to be kept in groups of at least three, and -like goldfish- weather loaches require plenty of room. Combining the two will require a large tank. Weather loaches do like to burrow, so keep in mind that smaller sized rounded gravel or a sand substrate will be needed.
Rubbernose and Bristlenose Plecos
Rubbernose or Bristlenose Plecos are also frequently recommended, and make good choices as well due to their voracious algae eating. These plecos enjoy temperatures in the 72 to 77 degree range Do not, however, get the common pleco, which may be prone to sucking the slime coat from goldfish as previously mentioned.
White Cloud Mountain Minnows
Despite their small size, White Cloud Mountain Minnows are frequently recommended as good goldfish companions due to the fact that they are also cold water fish. In fact, White Cloud Mountain Minnows can be kept in temperatures as low as 45 degrees, but no higher than 75 degrees.
UPDATE: A reader has commented that white cloud mountain minnows attacked his telescope goldies. I don't think I'd keep anything with telescope goldies, other than perhaps a couple of snails, and should have mentioned that.
Zebra Danios have a temperature range between 65 and 80 degrees. These minnows make good choices, as long as the goldfish are not fancy. The minnows will generally be fast enough to avoid hungry goldfish who mistake them for a snack, but too fast to allow a fancy goldfish a chance to eat. For pond keepers, Zebra Danios are also recommended for use in outdoor ponds. It is said that they enjoy eating mosquito eggs.
Rosy Barbs can be a nice choice as well. These subtropical barbs are not aggressive, and very similar to goldfish in appearance, but with a pink hue. They grow to be 4 to 6 inches at maturity, so generally aren’t considered snack material, and their ideal tank temperature is 65 to 72 degrees.
All of the fish I have mentioned above other than the plecos will be most comfortable if kept in groups, so that must be taken into consideration. Schooling or shoaling fish not kept in groups tend to become more aggressive than they would otherwise be.
While Apple Snails and Ghost Shrimp are commonly recommended, there is also anecdotal evidence of these aquatic animals being eaten by goldfish. Generally the Apple Snail will present too much difficulty for eating, but may still be harassed by goldfish if they haven’t been raised with Apple Snails. Ghost Shrimp can usually escape a hungry goldfish, but not always. They may survive better with the fancy, slower goldfish, however, most ghost shrimp are sold as feeder shrimp, and therefore not usually given a great deal of care in the breeding. This is why any fish store tank of ghost shrimp typically include a good number of dead specimens. By introducing ghosties to your tank, you may be introducing disease. Be sure to quarantine in a separate tank to insure healthiness before adding to main tank.
All that said, you cannot always predict what a fish might do. Just because a certain fish is listed at the store as ‘peaceful community fish’ and the stated temperature range is appropriate, it’s best to come home and research the fish on the web first for further information before you purchase it. This is true no matter what kind of tank you have or what kind of fish you seek.