need help with koi - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 4 Old 03-15-2012, 08:55 AM Thread Starter
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need help with koi

i am making an indoor koi pond/tank
it will be 90 gal with 1000-1200 gph pump
running with a bio filter filled with bio balls and foam and filter fabric

how many kois will i be able to keep in this tank?
it is 4ftx4ft x 10in

i have a dog named fish

30g long

55g -planted

125g 4ft long octagonal


10g hospital
-empty- :]
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post #2 of 4 Old 03-15-2012, 12:03 PM
Mo's Avatar
Koi (Cyprinus carpio) have an average size of around 3 feet, like to be in groups, and have a very high bio load. There fore would not be suitable for a 90 gallon, 4 foot tank. Ideally a 700 gallon tank is needed to keep them happily and let them reach there full potential. So, the amount of koi you would be able to keep is zero. Have you thought about having fancy goldfish? As the streamlined ones will ideally not be comfortable in that tank. There are many types of fancy goldfish like

Oranda goldfish
Telescope eye goldfish
Ryukin goldfish
Pearl scale goldfish
Ranchu Goldfish
Fantail goldfish
Bubble eye goldfish

They all stay relatively small for goldfish (around 10 inches or so) are very easy fish, and are very entertaining, they will have a personality of there own as bettas do and you'll definitely enjoy them

Fancy Goldfish are very entertaining fish, they have a personality of there own, and are very funny to watch, the way they swim, the way they swim against the glass to get your attention, the way they'll eat off your finger, they way they eat, and spit out the gravel, it's very fun to keep them.
They aren't as hardy as there closely related common, streamlined, larger goldfish. Though they can still tolerate a wide range of PH, and hardness. They don't do well in temperatures below 40 or don't do well in constantly fluctuating temperatures. Never keep them in undesirable conditions eaither as they won't last long due to the fact of how fragile they become after being introduced to constant bad conditions
They also are very susceptible to Swim Bladder Disease due to there body shape, so watch out with over feeding, and take precautions when keeping them to prevent Swim Bladder Disease from happening like fasting a day with a pea

Last edited by Mo; 03-15-2012 at 12:17 PM.
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post #3 of 4 Old 03-15-2012, 12:31 PM
Mo's Avatar
Fancies stay relatively small for goldfish, they stay around 10 inches or so, but still have a very high bio load, so ideally you should heavily filter the tank, and cycle it before you place any fish inside
You might have a bit of trouble with plant selection as they are omnivores but will have a feast in a planted tank, ideally you want to go for hardy plants like hornwort, anacharis, anubias, And cabomba, these are all relatively easy plants that do well in goldfish tanks and can withstand the constant pecking, they will do well without high light, fertilization, or added Co2.
Goldfish also, really like high oxygen content tanks, so if you could, get a large airstone along with a powerful filter to creat the amount of desired oxygen that they do best in

Last edited by Mo; 03-15-2012 at 12:38 PM.
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post #4 of 4 Old 03-15-2012, 12:53 PM
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I agree with the above. Koi are not suited for anything less than 1000+ gal ponds as they are massive fish. I have about 6 in a 4000 gal pond and they do school much more tightly than you would imagine. The smallest ones never want to be away from "the group." Unfortunately no matter how large the filter is, it can't make up for swimming room.

A school of 6 or so fancy goldfish is best suited for your tank. Commons like comets, and shubunkins like a little more swimming room. This is a list of the more common goldfish breed accompanied by pictures.


Sitting by the koi pond

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