Akari's Common and Comet Goldfish Care Guide


Common Name: Carassius auratus (Common and Comet Goldfish, Goldfish, Feeder Goldfish)

All Goldfish were bred from the Crucian Carp (Carassius carassius), which are found throughout Asia. Common and Comet Goldfish are a commonly kept aquarium and pond fish that come in a variety of colors. They grow quite large if they provided with the space they need to so. They tend to be very peaceful, though some individuals can get pushy when they feel cramped or when breeding and they do have spines on their dorsal and analfins, so care should be taken when netting and handling larger fish, and check over females and other fish for injuries during breeding season. Goldfish have been known to live into their teens, and accept a wide range of water conditions. They enjoy rooting around in the substrate for food.

Sexing: The only sure way to sex Goldfish is to wait until they are of breeding age, usually 1 ½ to 2 years old. Males will develop tubercules around their gill plates, face, and the front edge of their pectoral fins. Some will even develop tubercules down on to their bodies and fins. Males tend to be slimmer than females, and the area between their ventral and pelvic fins will be concaved. Females are fuller in the body, and are more flat or rounded out between their ventral and pelvic fins.

Fish Size and Housing: Given the space and care, Common and Comet Goldfish will grow more than 10 inches long. In one year, they can typically grow from a few inches long, to more than 8. A minimum of 55 gallons for a single Common Goldfish is recommended, and no more than 2 in a tank of this size, as they are major contributors to the bioload, though an even wider tank is better, to provide extra room to turn around. Really, large pond is ideal. More surface area allows for more fish, in a reasonable sense, as there is more room for gas exchange. In a pond environment, you can afford as little as 20 gallons per fish, as long as you are willing to step up on water changes a bit. In the aquarium, provide a sandy substrate (or no substrate at all), and thick leaved plants like swords, anubias, cryps, and java ferns (or silk plants), and décor large enough for them not to get stuck in. Plants are typically targeted as toys and treats. Keep this in mind when adding them to your aquarium or pond, as they may be uprooted, or eaten. Goldfish are a hardy fish that accept a very wide range of conditions, as long as Ammonia, Nitrites and Nitrates are kept at their proper levels. They do seem to prefer water that is not too hard, but if acclimated properly, usually do just fine.


1 ½ year old Female Common Goldfish

Food: Goldfish seem to enjoy a diet that is mainly made up of plants and vegetables, through a higher protein food, with more frequent feedings (and more frequent water changes) will increase growth. Avoid foods containing corn, corn meal, and the like. If keeping your goldfish in an outdoor pond, it is best to feed a diet with wheat germ in the fall, and early spring. This helps them digest their food in lower temps, and also provides some extra protein when the insect populations are lower. When the water temperature is below 50*F, you should not feed them. They will slow their metabolisms and eat very little.

Breeding: If kept outdoors, Goldfish typically breed during spring, as water temperatures start to rise. They can easily breed year round, as well, as long at the temp is high enough, and their diets are right. As temps start to fluctuate in fall, they will attempt to spawn a few more times, before becoming dormant for the winter. Aquarium Goldfish seem to breed whenever they are ready, but do stick with the usual springtime fling, as well. Males will get pushy and sometimes even aggressive with females and each other. Males will nose and push at the females ventral area, trying to entice the females to release their eggs. The fastest male to make it to the spawning female will fertilize the eggs. Be sure to keep more mature females than males, to reduce stress levels, and remove any females that are being pushed around too much and are unwilling, or not ready, to breed.

Tank Mates: Goldfish are typically very peaceful fish.They are commonly kept with other Goldfish and other temperate community fish. It is not suggest to keep Long Bodied Goldfish, such as Commons, Comets, Shubinkins, and Wakins, with smaller Fancy Goldfish, like Ranchu’s and Lionheads, or Fancy Goldfish with deformed eyes, like Bubble Eye’s, Celestial Eye’s and Telescope’s, and with Oranda’s with exaggerated wen growth.

Suggested tank mates: Other temperate community fish, most other Goldfish (see above), Hillstream Loaches, Mollies, Rosey Minnows, Dojo Loaches, Danio’s, Bristle Nose Pleco’s*. I have also kept Endlers with my large Goldfish with no problems. Always research each individual fishes needs before bringing them home!

*Pleco’s can be tricky to keep with Goldfish. Some individuals will eat away at Goldfishes slime coats, scales, and skin. This is true for most types of Pleco’s, and especially true for Common Pleco’s. I am currently housing a 4 inch long Common Pleco in my 150 gallon pond with Goldfish ranging from 3 to 8 inches, and a 4 inch Goldspot Sailfin Pleco in my 65 gallon pond with Fancy Goldfish ranging from 4 to 5 inches, with no problems. As the Pleco’s both age, issues may arise, so if you do decide to try housing any type Pleco with Goldfish, always keep an eye out, and keep both parties well fed. The most common type of Pleco housed with Goldfish are Bristlenose Plecos.

Common or Comet? While all Goldfish share the same scientific name, selective breeding has produced a large variety of true-breeding body types, fin types and colors, like how we have such a variety of dogs, from Chihuahua's to Great Danes. The difference between Common Goldfish and Comet Goldfish is simply fin length. Comet Goldfish will have longer, flowing fins, while Commons will have shorter rounded fins. As both types age, their fin length will increase dramatically, and it is possible that may be difficult to tell apart. Common Goldfish will typically have caudal (tail) fins that make up less than half their total length (from nose tip to fin tip) and Comets will have a fin length that makes up more than half of their total length. Fin length may or may not need to be taken into account when housing these fish. Fish with very long fins may need larger tanks that allow for more space so that their fins are less likely to get caught on plants and décor.


Young Common (Orange and White) compared to a young Comet (White). Note the difference in fin length.



Thanks for sharing!


Thanks Akari. This will come in handy for when I build a fancy gold fish pond.


Sure thing

In a pond environment, I like to allow 30 gallons per fish because water changes aren't as exentively done on ponds. Obviously, the larger the pond, the more this can be fudged, but with anything you can buy at a home improvement store, this is about the stocking level you'll want to stick with.


Super cute!!! <3


Thanks! You should see those two smaller fish now lol They're huge!


How are the goldfish??


Hello, first off thanks for the information it was quite helpful. Now second, I have a bit of a dilemma. Shortly before Christmas my partner bought two comets for our RES turtle(he's 2 yrs old at about 5-6inches). We now have 7 feeder fish(avg. under an inch each), Donnie, and now the two 1 inch &1/2 comets all living in a 20 GALLON TANK!!! Our turtle Donnie is much too lazy to catch fish, and now will only eat them when hand fed. Our local pet store did not tell my bf anything on care for the comets and sold them as an "appropriate feeder for our turtle". I did not want to send them back knowing the conditions would be even worse there... We are looking into a 100gal tank for our turtle as his recommended size tank at full age is approx. 75-90gal being a male. Do you think that size tank could keep the comets happy with Donnie? They don't seem stressed and have actually become regular(and quite fearless) turtle groomers, Donnie leaves his feet in the water while basking and they help exfoliate rarely scurrying if he moves. We have been letting them clean the tank and when they seem overly peckish we give them a pinch or two of flakes. Is this ok or should I be discouraging Donnie from allowing this? I am hoping the feeders number will go down as his fish feeding days go by and we can then manage it, my bf got the lecture and now knows no more fish without the room! I realize this is a fish site but would it be ok if he ever did snag one? (we never allow seriously wounded or ill fish to remain in the tank, we also try to discourage breeding as we had a very big incident where we were not prepared at all thanks to the pet store and our own lack of research on the peculiar occurrences). The temperature is currently at 76f but will decrease as the turtle grows, but never going below 72, we check the Ph every 3 or 4 days as it stays rather neutral is this all ok? We have a 40gal filter to help maintain the turtle waste so the water stays rather clear and algae production takes a while to start and then gets scrubbed away before 40-50% water changes or a grand cleanout) however I worry could the current be a little strong at times? You said they can live into their teens, do you mean developmentally or age? Our turtle can have a lifespan of up to 30 years or more so there's not much budging on making him change habitats unfortunately he takes top priority here.


I don't know much about turtles, but I can give you a few pointers.

Since he doesn't seem too interested in the fish, I'd say it's alright to leave them together. I would get him feeding on a high quality pelleted diet (many reccomend Mazuri's. It's available at PetCo for $12 for a decent size bag.Omega One also makes a turtle food) as well as looking into what veggies he can eat.

Goldfish are not good feeders at all because they are very fatty and often carry parasites and diseases-- even if you can't see them. They make great pets though. Kind of like soggy puppies that you can't cuddle.

Goldfish don't really care much about pH, but I'm not sure about turtles. Someone else would have to advise you on that.

As for tank size and filtration, I'd get a tank a bit larger than 100 gallons so that you can have some extra space and plenty of room for as much water as possible (goldfish get large and poop way too much for their own good) while still having basking room at the top of the tank. I'd suggest 130-150 gallons. I'd also look into getting two canister filters, and have them rated together to filter 200 gallons. Do not under estimate the ability of turtles and goldfish to poop. Also make sure the turtle has access to UV on his basking platform. This is essential to processing nutrients, namely vitamin D and calcium.

Both goldfish and turtles are very longlived. Goldfish are known to live a few decades if cared for properly. Feed them well and give them lots of space and they'll live longer than the average small dog.

I'm also going to have a mod move this to its own thread, so that more turtle people can help you


Thank you, I know most things about my turtles needs(we've had him for over two years) which is why I was worried about compromising the fishes possible needs for Donnie's. We try to vary his diet and fish feedings are quite rare as he's moved on to the more leafy greens stage and protein every other day(he gets a mixture of meal worms which are fed high amounts of vitamins and shrimp/pellets).Fish are no longer a feeder in this house, thanks to your helpful information! We knew about certain parasites, ie. nematodes etc. Which we were told if one was seen on Donnie to just pull it off and the fish couldn't carry anything harmful... However I feel they're kind of like ticks in the fish world so I believe this could leave like the head attached wouldn't it? We check our tank daily for unwanted visitors and noticed the fish seem to take care of these for Donnie and each other.
As for the tank the bigger the better I guess, my bf has decided to set aside a decent budget so we can hopefully keep everyone happy as we have noticed some peculiarities..
Now this is going to sound totally strange, but you can probably imagine how strange it was too find. The other day I noticed that one of the little rosies has made best buddies with our larger comet fatty, that wasn't what boggled me. It seems they have claimed the half log in the tank as their personal hangout, as well as pulling Donnie's pellets down so they get trapped and stored, but rarely eaten.. They have even tried to deter Donnie from swimming around the log as well as all the other fish! They're being quite bullish and I am hoping they aren't mating?(The last time we had rosies acting like this we woke up to hundreds of live babies!!) Its the difference in species that's what's mostly puzzling to me as I didn't think its possible, and further more non of the conditions are overly idealistic for breeding based on my knowledge. Sometimes the comet will leave the cover but usually only to swim around a bit with the other comet.


What is the right temp for a comet goldfish in an aquarium? *Headtilts*

Yeah I actually was just stopping by the pet store to get fish food and saw the feeder tank and couldn't leave without rescuing one I am going to put him in a 3 galling tank with a thermometer, filter and light, as well as all the usual decor. But I just want to be sure of what the ideal temp for a comet/feeder goldfish is. He is tiny, and I plan to upgrade his tank as soon as I can afford it. Any help please?


Sorry I missed your post!

I keep my indoor fish at room temp. About 76-78. I have a heater set to 75 so that the temp doesn't drop too low in the winter months and make them want to hibernate.

Don't keep him in that tank for more than a couple weeks. Healthy young goldfish can grow at a rate of an inch a month, given the space, food and clean water.


A correction to the original post: Carassius auratus and Carassius carassius are two distinct species. The first is asian, the second is essentially eastern European. Goldfish were not bred from the Crucian Carp, they were bred from the Asian species auratus. The wild form is still found in parts of Central Asia and China.


Hello @akari! I agree with almost everything on your care guide. The only thing I disagree on is tankmates. All of the fish you posted either prefer warmer temperatures (can't tolerate lower than 21 C) or they get very very big, and don't allow for best goldfish treatments, like the heat and salt method for ich. That can't be done with scaless fish like hillstreams. Also, most goldfish will devour danios or minnows or tetras. I have seen many pictures of a 5 inch goldfish with a betta in his mouth, and bettas get much much larger than tetras and danios do...

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