Keeping other fish with goldfish

Keeping other fish with goldfishWhat other fish can you keep with goldfish?

The first thing to realise when considering which other fish you can keep in the same tank as goldfish is that goldfish have very specific requirements and any fish you keep with goldfish will therefore need to thrive in similar living conditions.

Here’s a list of just some of the attributes of goldfish that you’d have to consider carefully when deciding whether any other type of fish would make a suitable tank mate…

– Goldfish like relatively low temperatures – they’re not tropical fish and will not be comfortable in high temperature environments

– Goldfish can grow to be very large and need a lot of space – you should never keep goldfish in a bowl, or in a tank that is too small for them. Any other fish that you add will be taking valuable space away from your goldfish.

– Goldfish eat a lot and will try to eat anything that will fit in their mouths… including smaller fish!

– Goldfish produce a lot of waste, which can pollute tank water – and more than one fish puts even more strain on your aquarium filter

– Goldfish scales can be damaged fairly easily, and some fancy goldfish have “bubble eyes” that can be damaged too (the Black Moor, for example)

So, to keep other fish with goldfish; you need to find a type of fish that:

– Likes similar temperatures

– Will not do any harm to your goldfish

– Is big or quick enough for your goldfish not to eat them!

– And you need to make sure that your tank is big enough, not just for your goldfish, but for the goldfish tank mates you plan to keep in it as well.

This is quite a lot to ask! And that’s why our advice is to only keep goldfish with other goldfish.

Not only that; we also advise against mixing common and comet goldfish with fancy goldfish. This is because the slower moving, poorly sighted fancy fish may struggle to compete for food, or have their long, flowing fins nipped by the other fish.

We know this probably isn’t the answer you wanted to hear, as it can be very tempting to add more fish to your tank! However, we would strongly advise that, if you do want to start keeping other types of fish, you get a new tank and keep them separately to your goldfish rather than keeping them all together as tank mates.

But what if you REALLY want to keep other fish with goldfish?!

Ok, if you absolutely must add another type of fish to your goldfish tank, we’d suggest either White Cloud Mountain Minnows or Zebra Danios. But you’ll need to make sure that your goldfish aren’t too big (ie. that they won’t be able to fit the smaller fish in their mouths)  – remember; your goldfish will grow! – and that your tank is big enough.

Also, Minnows and Danios are schooling fish (they live in groups) so you shouldn’t just add one or two. You should add at least three – preferably more like six – and that will require quite a big tank when you consider how much space your goldfish already need.

Remember: We strongly recommend that you keep common goldfish with other common goldfish, fancy goldfish with other fancy goldfish, and never mix goldfish with any other species of fish.

Read more in our Goldfish Care series.


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  • Jane

    How about a cory catfish or else some other breeds of catfish? Koi fish are pretty good too I would imagine. This is a great post here. I think the captions you are doing are super funny and I especially like the blackmoor one you did.

    • TheGoldfishTank

      Thanks Jane. Cory Cats are a possibility, but our two main concerns would be:

      1. Size – both of the tank and the relative size of the fish.
      2. Ammonia – cory catfish can be quite sensitive to poor water conditions, and obviously goldfish can be very messy!

      We’d say they fall into a similar category as minnows and danios – potentially compatible with goldfish, but we wouldn’t really recommend it.

      Glad to hear you like the pictures! The aim is to give the site a unique look and make browsing a bit more enjoyable – hopefully they’re doing that. :)


      • Marsha Jewell

        I have a 100 gallon tank for 8 large fancy goldfish. I learned the value of keeping an ammonia monitor hanging on the tank (need to replace every 6-8 months) as my daily backup to my water tests. The only other tank fish I keep are 6 cory cats that are each over 1 inch long. They have their own cave in one corner of the tank I dubbed “cory cove” – that the goldfish can’t get into easily, with their cave, a sunken ship hideout, lots of plants nearby, and the 1 heater for the tank is behind the cories’ cave. My goldfish tank is kept at room temp. My experience over the past 3 years with the cories kept with larger (3-4″) goldfish is that if the cories aren’t at more than an inch long, they’re too small! And cories need access to an area of the tank that has warmer water. My cories get very active scavenging the entire tank at night when I switch to moon-light blue LED light. My tank is big, and I’ve tried hard to make sure everyone’s needs are met and the cories are not just an after-thought “decoration” fish. For me, this set-up has done well now for 3 years. 2 of the 6 cories are almost 3 years old now, as are most of my fancy goldies. But it might help that fancy goldfish are slow movers and peaceful, friendly little guys. I’d never put cories in with super fast comets! Good luck to you on your tank! And many thanks to The Goldfish Tank site for sharing their wealth of knowledge! I have learned so much!

        • TheGoldfishTank

          Thanks for the comment Marsha – we’re really pleased to hear that you like the site and your tank sounds fantastic!

          It’s great to hear that you have several fish that are a few years old – you’re clearly doing an excellent job of caring for them!

          Thanks again,

  • Allie

    Ok. So I currently have a comet goldfish in a bowl (yes I know it’s terrible, but I got the best I could buy, it’s about 2.5 gal) and am thinking about getting a bigger tank for my comet. The sizes I’ve been looking at range from 10-20 gal. But in my opinion that seems like SO MUCH WATER. You know what I mean? For just one little fish? Will he grow as I increase my tank size? Like if I put him in the 10 gal with some plants and decor and what not will he? Then when he does grow bigger should I increase the tank size? I just want to do what’s best for the little guy and keep him happy and healthy. He loves getting his little pellets everyday and is pretty active. I need advice for a first time goldfish keeper.

    Also I change his water about every three days to keep it clear and i make sure to put stress coat in. Is this adequate until I get a bigger tank with filtration?

    Oh and sorry for the novel :s this comment could be helpful with anyone in the same situation as I am. I just don’t get why they need so much water. If someone could explain that, it would be marvelous.

    Thanks a million! [:

    • TheGoldfishTank

      Hi Allie,

      Thanks for your comment. And don’t worry that you’ve started out with a goldfish bowl – it is very bad for your fish, but it’s a mistake that a lot (probably most) goldfish keepers make when they get their first fish, and it’s not too late to fix it.

      The reason that goldfish need such a large amount of water is that they produce a lot of waste. This waste will seriously harm your fish’s health (and will most likely lead to a very short life) unless your tank contains a “colony” of “good bacteria” which convert the waste into less harmful chemicals. Unfortunately, in a goldfish bowl or small tank, it’s impossible for enough bacteria to build up to get rid of all of the waste and keep the water “clean” enough.

      So, a large tank has two advantages:

      1) The water gets less polluted because there’s more of it (i.e. the same amount of pollution is diluted into a lot more water, which is less harmful to your fish)
      2) There’s more room for bacteria to build up in gravel, in your filter, on decorations and on plants.

      There are other advantages too. For example, the larger surface area of a big tank allows more oxygen to get into the water, and your fish has more room to swim around.

      For comet goldfish (which like to quickly swim around a lot) we actually recommend a 30 gallon tank. This is enough for your fish to grow quite large and still have enough room. However, if you really don’t have room for such a big tank, you could start out with a slightly smaller tank for now. We’d strongly advise that you get as close to 20 gallons as possible, as 10 is still very small.

      Goldfish’s growth can be stunted by living in a tank that is too small to them. This leads some people to believe that it’s ok as “goldfish grow to the size of the tank”, but stunting your goldfish’s growth is actually very bad for your fish, and they’d be unlikely to live very long. If you get your goldfish a nice big tank – with a big enough filter – then he could potentially grow to be very large!

      You should read our post about “cycling” your goldfish tank and keep an eye on your water parameters using a test kit. In that post, we advise against cycling a tank with the fish already in it… but, in this case, as you already have your fish, we’d suggest moving him to the bigger tank straight away, and continuing to do large water changes even once he’s in the big tank (until you see your water test readings start to improve).

      In the meantime, keep do a lot of water changes. We’d suggest changing around half of the water every day, rather than every three days. And keep using the stress coat to treat the water.

      Hope this helps! Let us know how you get on!


  • Daisy

    I have a total of 14 fish in my tank yes that’s a lot of Fish, 11 of them are goldfish and the reason I have so many is my goldfish keep laying eggs I have smaller tanks aside for that so if a family member wants a fish they don’t have to go to a pet store to get one they just come to me. My golds have layed eggs in November, December, then again in February and March I also have plecos in my tank but I did not know that you aren’t supposed to have them and goldfish together in a tank because the pet shop I purchased them from did not give me that kind of information that was 8 years ago that I have got them, to this day they do real well together, I have 4 comet goldfish one black moore and 2 plecos, and 6 babies, with frequent water changes until I get my bigger tank they do great!

  • karin

    i have five, started with a comet that was from the fair that was 8 years ago it is 7 inches long now, I had him in a 30 gallon tank with filter ad added a common gold fish i got as a feeder fish for .25 cents that one is 5 in now. I just made them a 50 to 60 gallon pond and wanted some color, so i added Shubunkin Goldfish, these guys are orange, black and white calico goldfish. I also got another large tank for winter

  • ccrider77

    I have a small desktop tank at work and a 20 gallon tank at home. At work I keep a small calico Moor for now, and he gets along fine with my small catfish and bloodfin tetras. The tetras are usually top swimmers and very fast and the cat is pretty elusive, hiding in the plants and decorations near the bottom most of the time.

    At home I have a pretty large fantail comet and orange Moor, which get along well. We added a Chinese algae-eater and they leave each other alone. We keep the tank at 72 at home, which is on the cold side for the algae eater and at the high end for the goldfish. We also keep the algae growth fairly high in the tank to minimize any competition.

    I wouldn’t hesitate to put other community fish such as cats or tetras with goldfish, provided the size, speed, temperature, oxygen demand and habits are compatible. Obviously goldfish eat a lot and require more O2 than other species, so overloading a tank with too many fish will result in death for the less hardy specimens.

    Just my opinion…

    • Bekah

      Do you only have 1 cat in that tank at work? He/she must be really lonely that’s why it’s always hiding. even though you have a small tank at work, you can still add 2 more cats, at least that one will have company, and you won’t see them hiding anymore. I have catfish in my tank and they love to swim everywhere and love to swim in the middle as well, of course they are in groups always. Just a suggestion.

  • tawsif

    i have a goldfish in a bowl but now i got a 10 gallon tank with gravel filter light and fake plants im cycling it with good bacteria. its been two days can i just put my goldfish in and let it cycle rather than keep it in the bowl for another couple weeks before putting it in the tank?

  • Mike

    Can i put Koi and Goldfish together?

  • Iris Levario

    Okay, well. I need help you guys! Here goes. I’ve been a fish owner for about a month and a half. I have a 20 gal tank, I had 3 Tetra Fish, 2 Mickey Mouse Fish (that were inseparable), and 2 fantail Goldfish. One of my tetra fish, has been moving less. He usually spent time near the filter, (this is where I thought there was something wrong); after a week that tetra passed away, and wasn’t floating up, it was simply on the the pebbles, not moving whatsoever. After this incident, 5 days later, one of my Mickeys have been acting weird. Like I said, my mickeys were inseparable. He has been spending time near the other mickey; however, he goes near the filter just like the tetra that passed away. When i see him there, i tap the glass and he goes with the rest of the fish. I see him this at least 4 times a day, and has been happening for 3 days. Nonetheless, this morning i woke up to feed my fish and one of tetra fish was floating on the edge of the tank. He passed away unexpectedly. This is all very odd to me. My goldfish look happy, healthy, and with energy. My goldfish, however, love to play with my last Tetra, which is a Dalmatian Tetra. This Tetra fish, looks also happy, healthy, and filled with energy. What is going on with my fish? Any advice, anything, would help.

    • Allan Birmantas

      Your tank is drastically over crowded. One GF needs at least a 20 gallon tank, even if it’s a fancy. Sorry to give you the bad news. I had to learn the hard way. Also your collection of tropicals and the fancy GF are truly not compatible. I would recommend visiting Kokos goldfish forum, they can give you some really good advice, much better then mine.

  • OhItsMellissa

    I have a 12 yr old common goldfish and his tank mate died a fee days ago, was also 12 but a Japanese goldfish I believe. I’m having a hard tell finding another common goldfish of an acceptable size, at least 4 inches as my goldfish is a hefty 8 inches long fella. Any suggestions on a new tank mate as he is very depressed

  • Bella

    I used to have 5-6 24-karot fish in a 40-gallon tank with my goldfish. They were just fine, because they were too big to fit in the goldfishs’ mouths. But, after a few months, the goldfish got too big and started eating the fins of the 24-karot fish. So i put them in another tank.

  • Sherwin Hashemi

    Hi,i have a 1″ redcap oranda with a 2″ koi they very good with each other and the oranda chase’s the koi every were .There in a 15 gallon tank with two mystery snails and a strong filter . I want to know if it’s okay to keep them like this.

  • Allan Birmantas

    That does sound like Ich. Buy a bottle of medicine and follow the directions exactly.

  • Rachel

    What are some possible good fish to have besides goldfish. I have 3 gold fish in a 20 gal right now and my friend just gave me his 29 gal. I want to put something cute and active and bright colored to fill the tank so it’s not collecting dust. I’ve only done fresh water before but people are saying try tropical or salt water fish. But I don’t know how to care for those kind.. Please help