View Full Version : Two-foot Koi in approx. 150-200 gallons. How do they do it?

04-19-2009, 7:41 PM
When I go driving or walking sometimes, I see living rooms with koi aquariums. I'd love to keep koi inside, but their bioload is a frightening hurdle. What would prompt someone to wrestle like that?
I can't imagine the maintenance on these tanks I've seen. Can a koi live its full lifespan in a tank like this? Is it even worth considering? I'd think not, but having seen it done, and the fish seeming content, the idea is tempting. Does anyone have a large koi in an indoor aquarium of 200g or less? Not just for the winter, but permanently? How old can these indoor fish really get before succumbing to either poor water quality or malnutrition, or both?

Granted, they should reach three feet, but two feet is pretty good for being in an aquarium...or should I say bad?

04-20-2009, 3:35 AM
they will die of organ failure rather quickly if such a tight space

Mystus Redtail
04-20-2009, 3:51 AM
I bought my first 125 from a little old lady, who not only kept koi in it, but bred them in that size of a tank. She claimed she'd been breeding them that way for years, and I'm inclined to believe her, she had a 55 that she would put the babies in after she scooped them out of the 125. I ended up being given several large koi and dozens and dozens of babies of all sizes, many much smaller than I've ever seen in a store. I don't keep koi, so they all went to the store.

If you're wondering what she used for filters: 3 undergravels with 1140 power heads, 1 emperor 400, 1 penguin something, probably rated around 60gal. Fish seemed happy and healthy, and the water was clean and clear...

04-20-2009, 10:41 AM
Yeah. That's the kind of weirdness I'm talking about! It's almost like ignorance makes the fish invincible.

04-20-2009, 8:46 PM
so long as you dont overfeed, and have a 3-4x turnover rate with alot of media i dont see the problem with doing it, also do whatever WC's needed to keep your nitrates at 20ppm. koi should be able to grow and thrive in a tank barely large enough for them to turn around in.

12-07-2009, 9:37 PM
I have a 55 gallon tank with 3 koi and a red eared slider all under 6 inches long and an external filter rated for 100 gallon aquarium. They are all dirty animals but my nitrite/nitrate levels are as close to zero as anyone would like. the koi are robust fish, if you are able to keep other fish without having them die then you will most likely do well with koi.
I also suggest not to overfeed them, and if you can, hook up an undergravel filter setup to an external cannister filter and you should be all set.

12-07-2009, 10:05 PM
i would never keep koi in a tank, unless it was a couple thousand gallons. they are very active fish that require a lot of room. it just isnt right IMO

jr monster fish
01-07-2010, 12:31 AM
Koi have been captive a long time. In poor water (compared to the super-filtered water of today) while they were selectiveley bred. This=really tough fish. Ive seen koi thriving (great colors, looked content) and being kept long term in aquariums which they were 1.5 times as long as the aquarium was wide, and its length was 2ice that of them. I think theyre fine as long as they have good water and food, tank size is important, but not as much as other fish.

01-07-2010, 1:20 AM
i have a 300g aquarium with 3koi 18''+ each & 3koi 3'' 5'' 12'' they are well fed and seem happy always hungry and stay this way with weekly W/C of 250g

02-05-2010, 12:50 PM
I keep koi indoor during the winter. They are separated into 2 different tanks. A 1500 indoor built tank, and a 670 gallon show tank. I also have a 300 gallon QT tank.

I would NEVER EVER put koi in a fish aquarium. Fish are sized according to their habitat. They grow to their habitat as much as they can, and then you have to go bigger and bigger and bigger.

If you have done your research, Koi need at least 500 gallons to themselves because of their bio load, but if you have the filtration down, you can go with 200 gallons per koi.

When I first started with koi, I kept my QT fish in a 150 gallon tank, and I still ran into trouble with ammonia etc...

Reading this thread and hearing of the guy with the 300 gallon tank, it makes me want to ask him if he would enjoy living in a bathroom stall for the rest of his life because at 18'', 300 gallons with other fish is NOT enough of room.

Koi, are NOT goldfish. They are completely different. Goldfish are extremely hardy, koi are not. Koi are more sensitive than you can imagine.

I pray to god that you all will rethink keeping koi in fish tanks. If the fish is 1-2 inches, keeping it in a fish tank might be ideal until they grow a few more inches, but Koi are POND fish. They need to be in a POND.

studd muffin
02-05-2010, 3:49 PM
IMO kois are meant to be put in a pond but if you have a large enough tank for them, go for it.

02-05-2010, 6:27 PM
their koi not great whites the parameters r good i do believe they should be in a appropriate filtered pond but today ....

02-05-2010, 7:37 PM
LOL... this thread is 9 months old.

Some ponds on average are worse then a filtered tank... however Koi do put out a heavy bioload. I do have an 8 inch koi in a 55 gallon and I can say its a fight to keep it clean. When I got him(and another one) they were intended to be in 125... however because of moving the wife didn't allow the 125 to come to the new house.

I'm working on an 2600 pond for him.

02-05-2010, 7:40 PM
not for life by any means, maybe in 1000 gallon tank.
(bigger then average in the picture. but its a example of how big they can get)

jr monster fish
02-08-2010, 6:07 PM
not for life by any means, maybe in 1000 gallon tank.
(bigger then average in the picture. but its a example of how big they can get)
Bigger than average? That's the understatement of the century. I want it.

02-18-2010, 5:52 AM
Considering that with proper care, koi can and regularly do exceed 2ft and can reach well into 3ft in length, I think it is abhorrent to keep such an active, high-waste fish in small quarters like a tank under 300g. They are pond fish, pure and simple, if you intend on keeping them healthy and happy for the full duration of their lifespan and maximum potential of their size (unless you're one of the lucky few with a several thousand gallon tank). Part of ethical fishkeeping is providing for your fish's needs, not seeing how big of a fish you can cram into how small of a tank just for the sake of owning it.

I wouldn't even keep single-tail goldfish in a tank for any reason but growing out or overwintering; I had two foot-long common goldfish in a 75g, and not only was it a struggle to keep clean with great filtration, but every time they spooked, darted, tried to play, tried to jump, etc. they hurt themselves because the tank was simply too small for them to move about freely in. I now allot 100g per goldfish (I have three in a small pond, all males so that's it!) and they're extremely healthy, have great musculature, and have had very impressive growth rates.

02-18-2010, 6:34 AM
nice thread, good question. I bought these two from a breeder today both 5'' but they're headed for a ghetto made pond soon enough........i believe one is a Hikari.

02-18-2010, 6:55 AM
Goldfish of any kind kepts in not enough water well live short painful lifes. No matter what people claim it just can not be done unless you are using a drip system where the water is never old and always fresh and then the koi would get so huge they would be cramped and unhappy.
Please anyone reading this don't think this is ok cause a few people make it seem ok. Cause it is not.

02-18-2010, 4:16 PM
mshill90 that is a nice indoor pond! and to mgk, how old do you think that koi is?

02-18-2010, 4:17 PM
nice thread, good question. I bought these two from a breeder today both 5'' but they're headed for a ghetto made pond soon enough........i believe one is a Hikari.
nice pickup... you got a platinum and gold koi. lol i bet Neo would want em haha

02-18-2010, 4:39 PM
I have to agree with mshill90 for the most part, although Koi are very HARDY fish(I find it hard to say they aren't hardy being that they can survive very low temps on very little food). They cannot be bunched together. Also they tend to grow pretty fast (at least all the ones I ever owned) so 200-300gl tanks aren't enough for 2 or 3 Koi. They are stricly pond fish. I keep 4 Koi outdoors in a 1500gl pond all year-round. It has become a lil expensive over the years only because I've invested in good heaters for the pond just so it wont freeze completly over and a man-made raised pond cover( only for snow-storms, like the one we just had up here).

Tanks are only good for QTing your Koi.

jr monster fish
02-21-2010, 1:35 AM
mshill90 that is a nice indoor pond! and to mgk, how old do you think that koi is?
From what I've read (i.e. no personal experience) that thing would have to be ANCIENT. I would guess 50-75 yrs., but that is just a guess.

02-21-2010, 1:46 AM
mshill90 that is a nice indoor pond! and to mgk, how old do you think that koi is?
no clue. i don't keep koi but atleast 15, which is the age most are fully grown.

its rare to get koi that big because the breeders will cull the biggest and fastest growing ones. For two reasons they eat there small tank mates and usually have poor coloration.

02-21-2010, 5:50 AM
nice pickup... you got a platinum and gold koi. lol i bet Neo would want em hahahhahahaha i was thinking of his barra when i bought em!!!

02-24-2010, 10:16 PM
Some things you guys should keep in mind when it comes to koi, the bigger the tank or pond the faster your koi are going to grow. Smaller koi tend to be more active than larger adult koi. The koi that I have seen nearing 3' were at least 30 years old and the females were about 1' in diameter. When koi get over 1.5' long, they tend to slow down, they don't dart around and become more graceful in their swimming habits. One other thing I would like to mention, if I recall correctly, there are three strains of koi are usually sold. Each one has it's own personality and growth rate. I see no difference between an aquarium or a pond, just as long as both are the same volume.

06-12-2010, 1:52 PM
We have a place in Des Plaines, my favorite chinese place Tasty Cuisine, that has been keeping KOI in a 150g tank for at least 10 years. I asked the owner, and they do change the water almost completely every week. The oldest fish they have is 8 years old, been in the tank the whole time. It is possible, but will a lot of water changes.

06-12-2010, 2:08 PM
Good to see this thread alive and well. Many good points and interesting circumstances brought up. That big overwintering pond looks great and clean. And I sure hope nobody takes any ideas and puts koi in their 100g tanks thinking it will be okay. But it is interesting to hear of what has "worked" for some. I doubt the koi living in tanks will live as long or fully as they could have.

06-12-2010, 4:38 PM
One argument that IMO doesn't hold water(excuse the pun). Is that Koi only belong in ponds. Incase everyone forgot, fish in general should never be in tanks... they only belong in rivers but the fact that we do keep them. Why is it ok for RTC or TSN to be in tanks but not Koi?

Right now my pond is very nasty looking(green water) but my tank is very clear(my Koi are in the pond and happy).

It's seems Koi are more unhealthy in dirty ponds then clear tanks.

06-12-2010, 10:30 PM
Agreed, Warborg. If properly done, a tank is more secure than a pond as far as safety goes. But the standard monster tank is probably not going to house one koi for more than a couple of years. Most of us stop at between the 100 gallon and 200 gallon mark, and I take that into consideration when discussing koi in tanks.

Let's not forget how beneficial green water can be for growth and general health, though.