Two-foot Koi in approx. 150-200 gallons. How do they do it?

knifegill

Peacock Bass
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Sep 19, 2005
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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?
 

Mystus Redtail

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Jun 8, 2007
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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...
 

knifegill

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Yeah. That's the kind of weirdness I'm talking about! It's almost like ignorance makes the fish invincible.
 

perfect_prefect

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Jul 17, 2008
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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.
 

m1ste2tea

Jack Dempsey
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Nov 17, 2009
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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.
 

jcardona1

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Jun 5, 2007
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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

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Nov 17, 2007
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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.
 

JAFRIAS

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Mar 29, 2009
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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
 

mshill90

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Nov 4, 2009
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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.

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