Looking for Compatible Tank Mates for Koi/Goldfish - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 9 Old 12-15-2011, 09:27 AM Thread Starter
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Looking for Compatible Tank Mates for Koi/Goldfish

So i have a 30 gallon tank with, well i guess let me start a little earlier than that. if you would like skip over the origin story scroll down until you see a break and then the words "SO, I GUESS"

I lived in a house on Long Island with a fish pond in the back. We had a buncha different koi in it, and last winter the freeze killed a lot and then the crane got ahold of a lot but i guess b4 the bulk of them died, they let out a lot of eggs and whatnot because when we started the spring cleaning of the pond, there was about 40+ very tiny fish. they grew a bit over the summer, some larger than others, and about early-mid september I had set up a 30 gallon tank in my room and towards the end of the month i had added 7 of the summer fry (who were about an inch of so in length) into the tank. i then purchased a small Shubunkin Fantail, Black Moor Goldfish and two pleco. things were going well. one of the pleco died about a week or two later in the night. not sure why really, everyone including he seemed to be good b4 and after.
then the move came. late november i had to move to PA. i filled up a 5 gallon bucket with their water and poked a few holes and added a small bubbler to give them some oxygen here and there throughout the trip. well once they were all added to the bucket. i went to wash my hand some something for a few minutes and when i returned, one of the koi (which mind you look a lot like teenager $.18 feeding fish so im not to sure what they really are now) had died. I was expecting loss with the move but not from the tank to an inch or so to the right. so with that unfortunate occurrence behind me, i set sail, well engine and tires, to PA. when we arrived one more "koi" had passed, sad, but at least it had only been one.
i set up the new tank, worried about the apparently high metal content of the water in PA, in my room and after the smoke, well cloudy water, cleared the survivors of the 2011 move were settling back into their home. Then about two or three nights later, another koi passed. i woke up to him attached to the intake of the filter. i figured it could be the stress of it all and like in a move hes the one guy that cant survive after a hefty trauma. after that though everything has seemed to level out, they get a little pissed after a water change about the next day they seem better than ever b4 kicking themselves for doubting me.

so, i guess we now come to my question. with the remaining 4 "Koi", 1 Pleco, 1 Shubunkin Fantail, and 1 Black Moor, what are compatible tank mates. I have seen a few things here and there about goldfish needing to stay with other goldfish, but if water temp, pH and whatnot all fit into the same ganges of the goldfish, and they new additions are easy and peaceful, why wouldnt they be able to get on.
i have a few in mind that i have been doing a bit of research on, generically: cichlids, sharks, tetras, barbs, minnows, and a few others.
Can anyone help me out. if anyone has experience with keeping tropical freshwater fish in the same tank as koi and or goldfish, or has any knowledge/insight that can help i would greatly appreciate it.
and also sorry for the rather long winded origin story. i promise to try and keep things a bit shorter int he future.
Thanks again to anyone who can help.
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post #2 of 9 Old 12-15-2011, 02:35 PM Thread Starter
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oh and also, i dont really plan on keeping the koi/goldfish in this tank forever, we had the pond at the old house and plan on having another in about a year. so once the pond is in the ground, the majority of the fish will be in there with it. i have them in the tank now and just wanted to get some nicely coloured friends for them for a bit and then once the goldfish are gone, the friends that i have added will get new friends. i say this because i know goldfish like to grow, but im pretty sure they wont be reaching 18 inches in the next 12 months. i could be wrong though. lol. but please anyone who could shine a little light on my question would be of great help to me. :)
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post #3 of 9 Old 12-15-2011, 02:58 PM
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Welcome, Argo. I keep both koi and goldfish, so I hope I will be able to help you with this. First off, the pleco is not compatible with koi or goldfish. Plecos are tropical fish while koi and goldfish are coldwater fish. Also I have heard horror stories of plecos gaining a taste for goldfish slime coat and attaching themselves to the fish while they sleep. I would get him a new home immediately.

I know you plan to upgrade to a pond, but that amount of fish in 30 gallons for a year is going to cause some stunting. You are waaay overstocked which might be the reason you lost some of the koi: stress from the move plus being overstocked. The koi really should be put in a larger tank as soon as possible.

For pond fish, I would keep the moor out of the pond. They are considered "seeing-impaired" goldfish and will be out competed by the faster koi and goldfish. They also don't do well at the lower temperatures a pond will get to. I would keep the moor in the tank. You could get another moor buddy for him once the common goldfish and koi are in the pond.

Your tank is already way overstocked. I would not add any more fish until you have moved the koi and goldfish into the pond. As far as tankmates for afterwards, almost nothing does well with goldfish except goldfish. All the fish you listed are tropical fish and need higher water temps than goldfish like. Cichlids can also be nippy which is not something you want with goldfish. Some of those would be good tank mates for a pleco, but not goldfish.

Another reason it is generally recommended to keep goldfish in single species tanks is that they are VERY messy fish. They produce a lot of waste and this bothers most other fish. I have never had any luck with keeping goldfish with any other species.

Hope I was of some help!


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post #4 of 9 Old 12-15-2011, 03:53 PM Thread Starter
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i also plan on getting a heater for the tank and plan on keeping it around 72-75 since ive seen that a few have said up to 80 or 82 and even 90 for goldfish. im not going that high but i figured i could go higher than 68.

and also thank you, TheKoiMaiden, i was wondering about the pleco though, the local fish place at home told be to get a pleco or two to help eat algae and whatnot in the tank, knowing i had goldfish. also he said that for normal fish you do about an inch per gallon but with goldfish, because of the waste, you could do about 1 inch per every 1.5-2 gallons. and right about now they are only maybe max 2 inches each so that would be 14 gallons. but idk could be ive been hearing the math wrong.

so yeah, lol, thank you and im still pretty much a noob at all this so i will take as much advice as i can and i will take it all under consideration. thanks again,

Last edited by Argonautica3; 12-15-2011 at 03:56 PM. Reason: forgot something.
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post #5 of 9 Old 12-15-2011, 04:42 PM
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It's no problem. We all have to start somewhere.

The 1 inch per gal rule with goldfish is completely thrown out. This rule only applies to normal-shaped fish. Goldfish and other deep-bodied fish need much more. Generally, the consensus with fancy goldfish is 20 gal for the first and then an additional 10 gal per goldfish. With koi, I have heard the rule is 500 gal per fish. I have 5 koi in a 4000 gal pond.

I have mixed feelings about the heater. Koi and commons really don't like temps about 75F (when my pond gets above 75F the koi are begging for food constantly and eating everything in their path). Fancies like the temp to be about 75F. I don't heat my goldfish tank but that is because it is in a warm area that doesn't drop below 75F. Also remember, the higher the temp, the hungrier the fish will be and the more waste they will produce.

Now about the pleco: they don't help with algae as much as most people think they do. They also get huge 6+ inches and produce a lot of waste like goldfish. I would try to return him to the fish store. If you really want algae control try pond snails. But algae is just a fact of life with a goldfish tank. I've never found anything to control it. I have to scrub the sides every week.


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post #6 of 9 Old 12-15-2011, 06:19 PM
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Sorry for the double post, but I looked at the pictures of your fish. I don't think you have any koi (which is a good thing), but I want to be certain. Do you see any barbels on the mouths of your fish? If you see barbels, you have koi. No barbels mean just goldfish.

Another tidbit: koi and goldfish can hybridize. But another thing that makes me think you only have goldfish is that they are the ones that commonly breed in ponds. While koi can breed in ponds, most don't.

I've also added some reference pictures of koi, goldfish and hybrids just in case.

Closeup of a koi head. You can clearly see the barbels. All koi have these.

Goldfish/carp hybrid from the wild.

Goldfish. The body isn't as deep as the koi body. It also lacks barbels and the mouth has a distinctive upwards slope.


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post #7 of 9 Old 12-16-2011, 08:13 AM Thread Starter
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No worries TheKoiMaiden, ill take double posts and even triple posts if need be, lol. the more info the better. and you are correct my fish dont have barbels. the pond we had in the back was pretty big, and we had a couple different kinds of koi and some different kinds of shubunkins and a couple goldfish even a pretty big fantail. the koi's were beautiful (im gonna try and find a few pics that do them justice) but last winter when the pump and heater blew within the couple of days and it snowed and froze over bad, the largest which were the koi mainly, were the ones to kick the bucket first and then when the meltdown started to happen and we got them a bubbler to help bring in some oxygen it let out a lot of fish smell. basically it put up a giant neon sign "HEY CRANES COME AND GET IT" so yeah the crane got a few koi and goldfish and even the fantail. worst part was a few of the kois and fantail we had had for about 12 years and the others anywhere from 6-10. i figured if we had fry it would be from the dom fish in the pond. the largest and longest rooted ones.
i write all of tis one because i miss them and two i had been writing "koi" in quotes about my fish because i was just kind of unsure, lol, i didnt know if the barbels came at like 2 or 3 years old. like they were Koi's hairy arm pits. lol.
but thank you for that info, now i know i can stop writing koi and stop having to try and remember to put quotes around it too. lol.
oh and also the last pic you posted looks just like Tiger, the last fish i had to die in the move. i think hes in my first pic of my aquarium.
so thank you again TheKoiMaiden. :D much appreciated.
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post #8 of 9 Old 12-16-2011, 10:20 AM Thread Starter
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So this is my giant list of fish i think may be Compatible if anyone could say def yes or def not for me it would really help me out a lot to make the list smaller. i think i may be giving 3 or 4 of the fish to a neighbor. they have a big, i think 55 gallon thats just about empty and a pond. i think they have one or two in there now waiting for the meltdown to put in their pond. so yeah then ill have room.

Barbs - Gold Barb (Barbus schuberti),
Tiger Barb
Checkered Barb
Green Barb (Barbus schuberti),
Rosy Barb (Barbus conchonius),
Two Spot Barb (Barbus ticto).

purple passion danio
yellow long finned danio
danio tinwini
blue danio
red danio
celestial pearl danio
leopard spotted
long-finned zebra
malabar danio

Tetras - some of the more boisterous -
Head and tail light Tetras - maybe
penguin tetra
congo tetra
green neon tetra
cardinal tetra
glowlight tetra
serpae tetra
Bloodfin Tetra - (Aphyocharax anisitsi),
False Bloodfin (Aphyocharax dentatus)
Buenos Aires Tetra (Hemigrammus caudovittatus) - maybe, they will eat my plants.
Croaking Tetra (Coelurichthys microlepis) -

White Cloud Mountain Minnow (Tanichtys albonubes) -
Gold White Cloud

Red-finned shark - rainbow shark
red-tailed shark

Mollys - maybe

Guppy (Poecilia reticulata) - maybe

Platys - maybe

Rosy Bitterling - maybe

Pimephales (fathead minnows/rosy reds) - Fathead Minnow - Maybe

Panda Corydoras - maybe

SAEs (true ones!), - maybe

Sndlers - maybe

Sngels - maybe,

Harlequin rasboras - maybe


Goby -
Candidius Goby
Bumblebee Goby

Gourami - chocolate gourami - dwarf gourami - Paradise Gourami - maybe there are a buncha gourami

Otos - Zebra Otocinclus - Oto (Otocinclus mariae) - Dwarf Oto (Otocinclus macrospilus)

Wimple (Myxocyprinus asiaticus) - Freshwater Batfish.

Bluefin Notho

Blue Lyretail

Dwarf pufferfish - pea puffer

and these are the Cichlids

Saulosi - which i think are Afra Cichlids if they arent the same then most likely the afra cichlids because they are ok in a 30 gallon.

and these are they maybes
Convict Cichlid
Red zebra cichlid
Blue johanni cichlid

so anything anyone can let me know about the list would help greatly. hopefully its personal experience like, "i had three of these in with my goldfish for years and they loved it" would be the best i could hope for, but ill take everything i can get.
thank you :D
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post #9 of 9 Old 12-16-2011, 05:34 PM
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I'm really sorry to hear about your loss. I've had my pond for just 5 years, and I would be devastated if anything happened to my koi. Loosing something that old must be like loosing a child.

As far as tank mates for goldfish, anything that will be able to fit in their mouths is out. Goldfish will eat it. Trust me. I can't even keep snails in my tank because the goldfish see them as escargot. <_< This knocks off most of the fish on your list. As far as some of those other fish, I noticed that some are soft and acidic water fish. Goldfish like basic, hard water. Barbs and sharks are fin-nippers, and slow-moving goldfish make a good target for them. Anything that nips fins is a bad idea with goldfish. Also most of those fish are tropicals. Goldfish like cold water (especially the commons).

I don't know how much personal experience you are going to get with goldfish tankmates because most people keep goldfish-only tanks. A friend of mine on here has bichirs with common goldfish, but they are in a 55 gal tank. He eventually plans to put them in a 100 gal. I tried keeping dojo loaches with mine, but that didn't turn out well at all. The dojos took a liking to eating my veiltail's long flowing fins. I still think goldfish do best either in ponds with koi or in tanks with only goldfish.


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