Comet goldfish
If you want an elegant goldfish that’s as tough as it is pretty, the Comet Goldfish is for you. Sort of a halfway house between the Common goldfish and the Fantail, the Comet has a sleek, elongated body that ends in a single scissor-like tail.
Indeed, it’s called the Swallowtail goldfish in the Far East, which we think really suits it.
Comets come in several different colours, with gold and metallic fish and the orange-and-red Sarasa Comet amongst the most popular. In prize-winning fish, the colour of the body extends right into the tail; even everyday specimens in the pet shop should show deep, rich colours over most of the body. All Comets start life silvery green, however, which makes buying very young fish rather hit-and-miss.
In ideal conditions Comets can reach nearly a foot in length. Although their growth will be restricted in smaller quarters, it’s only right to give them as much space as you can spare.
Comet goldfish tips:
- As ever when buying goldfish, look for bright, clear-eyed specimens that take an interest in their surroundings.
- The tail shouldn’t droop at all.
- Comets are fast-moving fish that need a large indoor aquarium (ideally at least four-foot in length), or better yet a pond.
- They are pretty hardy fellows, and will happily live outside in most regions, provided their pond is deep enough for over-wintering.
- Comets love to shoal, so try to keep 4-6 fish together.
Comet goldfish seem to have been rather overshadowed in recent years by their fancier counterparts, which is a shame. Even purists who worry that man has tampered too much with some varieties of goldfish have to admit that the comet is a splendid creation.
Click here to learn more goldfish secrets!
Filed in: Varieties
May 14th, 2008 at 3:12 am
Hi i have a comet goldfish (still a baby) in a foot long tank , i wasnt told they get that big !!!
how long have i got until he does??
Oct 4th, 2008 at 5:45 pm
how about if the tank is 1 gallon
Nov 15th, 2008 at 7:38 am
@Rachel - Goldfish will grow far more slowly in small tanks than in ponds, but a foot long tank is not going to be a good home for more than a few months. Long-term you’ll need to get a 4-foot aquarium to really give your fish the home he deserves, or a pond. Fancier varieties such as fantails are better for small tanks.
Nov 15th, 2008 at 7:39 am
@Ryan - I’m afraid I don’t think a 1 gallon aquarium is suitable for goldfish for more than emergency quarters.
Feb 2nd, 2009 at 3:26 pm
i have several of the very small comets. do they stay this little or do they really get big enough to need a 4 foot tank?
Feb 15th, 2009 at 5:45 am
@Becka - your comet goldfish are babies. They will definitely grow larger with good care. In captive aquariums goldfish size does seem to be limited a bit by the size of the tank, but in my view they’re eventually going to need a four-foot aquarium to be happy.
May 27th, 2009 at 6:24 am
i have my goldfish in a 4 gallon tank.. is this going to be enough for him for now? until i can afford- and have space for- a larger tank as i’m moving in about 4 months.
Aug 4th, 2009 at 10:41 pm
Can someone please help me?!? I’m planning on getting my first goldfish soon and I was just wondering, does a comet goldfish need to live with other fishes like a Fantail?
Aug 7th, 2009 at 2:53 pm
I have one comet and 2 shurbunkins together in a 30 gallon tank. They get on really well because they are all fast swimmers - in fact, they seem to play “tag” together.
I did have a comet with a fantail but the fantails are much slower. Pretty, but not as interesting to watch as comets.
For sure, have at least 2, so they are not bored. But remember, they do grow. My comet is 6 months old (well, plus whatever age it was when I bought it) and is already 4 inches long. And at 2 months, the shurbunkins are about 3 inches, including tails.
Oct 23rd, 2009 at 1:04 am
I HAVE A COMET GOLDFISH ALL OF A SUDDEN ONE MY FISH HAS GAINED ALOT OF WEIGHT HE’S NOT NOT EATING AS MUCH AS SHE USE TO.CAN SHE BE PREGNANT?
Nov 18th, 2009 at 10:14 am
Hi i used to have a Common Goldfish and a Comet but the Common Goldfish died 1 month ago. They got on really well i think he died of age. I still have my Comet, he is 1 year old and he’s in a 12 gallon fish tank but i’m going to save up to get a 60 gallon one!
Apr 24th, 2010 at 5:19 pm
Hi! I have a Comet Goldfish! His name is Nemo! I am looking forward to giving him the best care he needs.
May 10th, 2010 at 12:32 pm
i had a comet goldfish that was 8 inches and probably 10 with the tail in a 55 g thats why it greww that much
Oct 30th, 2010 at 3:51 pm
I have 2 comet goldfish in a 1 gallon tank I want to get a bigger tank but I don’t have the money for one what should I do.
Nov 4th, 2010 at 8:06 pm
my gold fish is alone and it`s alive!?!?!?!Creepy!
Feb 28th, 2011 at 1:09 am
How did you make this blog site look this awesome!? Email me if you get the chance and share your wisdom. I’d be appreciative.
Sep 8th, 2011 at 8:31 am
I have just bought a black moor and a comet and have them both in a 10ltr bowl which i believe is about 3 gallons, i was told by the guy in the petstore that this would be ok, but after reading alot of the posts this does not seem so, especially for the comet, what about the black moor would that be ok, hope some one can help.
Sep 29th, 2011 at 1:47 pm
I’m getting to comet goldfish for my science fair project that I’m doing. I’m trying to find all the information that I can about comets. This is great information.
Sep 29th, 2011 at 1:47 pm
i like u
Oct 4th, 2011 at 5:57 pm
I Have a couple questions. i have 2 comets. the one is 6 years old and the other is 5. they had 2 sets of babies this summer. they are all brown. how old do they have to be to start changing colors?
Oct 8th, 2011 at 9:09 pm
i am getting a fish tank and a couple of comets for my birthday in about a week. is a 20 gallon tank big enough for both of them?
Oct 12th, 2011 at 12:32 pm
I have a 60gal. SetUp (4′L x 2′H x 1′D) The plan is to get One Comet Goldfish and One Sarasa Comet Goldfish. My question is Ive seen pics and in some pet stores “Common Goldfis” and “Comet Goldfish” Are they the same fish or are they just mis-labled at the pet store??
Oct 15th, 2011 at 9:58 pm
@Marc…
Are you looking in the “feeder” tanks like at Petsmart? They have them labeled as comets but I believe they are mixed with commons and comets.
I actually just got 6 fish from the “feeder” tank at my Petsmart. Some real pretty ones. .27 cents each. They all appear to be healthy as well. I have them in a 72 gal. bowfront but plan to move them to a pond (if I get it built) by next spring.
But they are lovin’ their new home right now. My tank measures 4 ft long, 12″ on the sides and bows out to 18″ in the center. The tank is 22″ deep.
I believe the comets are gonna have longer tails? I got one I believe might be a common goldfish as it doesn’t have the long tail fin. But I couldn’t pass him/her up. A beutiful red on top, white on bottom fish.
I love these fish. I wish I could build a huge pond and just buy all of them. I hate it they are used as “feeder” fish.
Oct 15th, 2011 at 10:08 pm
While I’m no expert, I still think you should have a 55 gal and up for these goldfish. They are swimmers. You may see them in the pet store, a bunch in a small tank, but that’s not meant to be a permanent home.
It’s like this. If you really want a goldfish, be able to provide it with the proper care it needs. Just cause you see them in bowls or small tanks, doesn’t mean it’s right. Another fact, the larger the tank the easier it’s gonna be to take care of as far as water quality goes.
My goldfish love to play in the current from my filters and the bubbles from the large 12″ airstone. I have 2 penguin 350 filters on a 72 gal bowfront (really only 65 gal of water after substrate/decor). So that’s over 10 times GPH. I have enough filtration for a 140 gal tank and only 65 gal of water. Good filtration is another big plus with keeping goldfish.
I read its a myth that a goldfish grows to the size of their tank. What happens is, you stunt their growth by putting them in small tanks. Their organs continue to grow. I believe this causes them to die a young age.
The pond I’m building is gonna be 8 ft long, 4 ft. wide, and about 2 ft. deep. Should probably be close to 500 gal.! I plan to only have comets and shubunkins.
Nov 1st, 2011 at 4:16 am
The body shape of the Comet is long and slim. They have a high dorsal fin and deeply forked long and narrow caudal fins. Comet has a tail lobes like open pair of scissors with metallic scales which is distinct feature from other goldfishes. It has single anal fin and long& pointed pair of pelvic, pectoral fins. Comet is fastest swimmer among all Goldfish varieties.
Nov 5th, 2011 at 4:50 am
I have 4 comets in a 4.26 Gallon tank (21 Liters)
is that bad
Dec 10th, 2011 at 1:57 pm
I have 6 comet goldfish I got the other day, for my science fair project, and I plan on keeping them, I wanted to research them and what size tank I need, as they were crowded ina small tank at the pet store. Thank you so much for your advise!!
Also, one of them died last night, I had them in tubberware bowls(very permanent, this is just until I move them to my other house and get them a bigger tank.) I had them all lined up behind a George Foreman grill, so ass to keep my cat away, and my dad told me one was on the floor this morning(cuz lastnight they kept flopping out of their bowls) and he flushed him, and I was thinking of getting another one or two to keep the others company, tell me this will the 4 foot tank be big enough to hold all the fish, and how long to they live?
Dec 10th, 2011 at 2:00 pm
By the way, “ass” is a typo, sorry, and we fixed the problem with them flopping out.Also, can Comets be paired with other fish? I would just like to know, too, at what age can you really begin to tell which ones are male and which are female? I was kind of planning on breeding sometime, but keeping them seperate for now would be a good idea. Do the “feeder” Variety get as big as the others?
Jan 16th, 2012 at 7:16 am
hello i am wondering I have and 1 and a half foot long would that be a good for a full grown comet fish?
Jan 21st, 2012 at 10:40 pm
I bought 6 comet goldfish and i have them in a 10 gallon tank is there a way i can keep them small enough to stay in the tank?
and 4 of them have already died in the past hour and 30 min can anyone give me advise
Feb 1st, 2012 at 1:17 am
Hi Andrea. Im a 1st timer and owns a 20l tank. I bought 2 comets 5 days ago and they are doing very well. They had their first treat of bloodworms yesterday and they absolutely loved it. 2 important things i remember having to ensure before adding the fish in tank, 1) is to prepare my tank environment for a good 5-7 days prior to getting the fish. 2) only add 1-2 fish to begin with and add another one after abt a week and another one in another week. I wad told that my little beginner fish tank is only suitable for 2 comets. And no more. By adding 6 fish at once, your aquarium ammonia level must have sky rocketed and kill them. Imagine 6 fish in a 10 gallon tank, u were only giving each fish less than 2 gallons of water to live in (eat, sleep, space etc.) think of it as a home for yourself and family
i added some little aquatic plants, little flat rocks and a drift wood to make my tank as natural as possible and ensuring the quality of the water and oxygen is at a good level. My advice is start small, get to know the fish, and read lots, just like what i have to do right now. 
All the best!