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koi growing


13 Aug 2008
Surrey, UK
hi all, this is a mixture of koi and aquariums but i thought it best to go in this section.

whilst i go to uni, i am unable to take my tank with me as they dont allow pets of any kind. (i thought, fish dont smell, dont make mess, dont make noise, dont need walking, and wont cover the room i fur!)
but anyway, i was thinking, can my parents use the tank instead of it just sitting empty and clogging up a corner of a room....

now we have a pond with some nice sized koi in along with a few small goldfish etc...
i was thinking, am i able to buy some fairly decent small high grade koi and grow them in the tank. this way i can control the temps and have it around 22 consistently and also really control the food levels.. this way growth can be fairly rapid....

although they are cold blooded they are warm water fish i believe so having some warmer water will suit them nicely. (hence they have been doing rather well in the wild of australia)

my tank is a 4x2x2 450L, with 2 ex1200's filtering it.
i have a K2 and a K.nano in there but i dont know if they will be needed with koi. (probably will as they like circulation)
i wouldnt have a substrate as they dont need one in ponds although some decor would be a bit nicer... (fake plants? wood? - suggestions)

would it be possible for me to keep some koi in there, and if so how many...

im thinking about getting some small 3-4" koi and perhaps growing them up to 10" and then selling them on..
yeah, i understand the major factors of koi growth are the following


now i will only keep a few obviously to keep the space they need to grow, otherwise it will be restricted. but i have no idea how many i can nicely keep in that tank...

airation is no problem as i have a TT APS air pump, or i can just raise the spraybars as i have no co2 to keep in, woohoo!
Keeping koi in tanks can be ok for a very short period of time but you won't get them growing well with good body shape up to 10" in an aquarium as they won't have the room to keep a nice body shape. Also many varities will also struggle to retain good reds in an aquarium and you can ruin the beni plate (the red colour areas).

Even if you do get them and grow them on don't expect to get much money for them as they will cost you more in good food than you could get back for them. Yoiu might be able to sell them for a bit more than you paid for them if you're very lucky.

I think I posted some pics of my growing on pond. That is 400 gallons filtered with a shower filter with a 12,000lph turnover and it's too small really for growing fish much larger than 50cm. It's perfect for getting fish up to that size though. Once your fish got to about 5 inches then they'd need a bigger space IMO and they can grow at 1cm per week if they're growing well so you'd only be able to keep them there for about 5 weeks if they're growing at their maximum potential.

In other words I think you'd be better off doing something else with the tank, sorry!
ah right okay, have to find another use for the tank. i dont really want to put ornamental goldfish in there as you can never offload them when you want them gone....
what about a dry start type tank your folks could just water it for you, and when you get back you have a ready to go scape.
i am away for 4 years, thats alot of watering etc.

and whn i come back i plan on using the tank for a mbuna cichlid tank so no plants needed. apart from perhaps a lily and some anubias.

i guess it will just have to remain empty.
Ive successfuly grown on small koi in a heated (70 degree) tank many times. The only major things to consider are they will totally ruin any plantlife you have, and depending on the protein levels of your food, may gain 4" in length within just 6-8 weeks and outgrow the tank before they are ready for outdoors! A 2" koi put in your tank at the end of the outdoor season (October) and fed a healthy, consistent regime, will be a good 8-9" by early spring and an ideal size to introduce to an outdoor pond. (not forgetting to acclimatise it for an hour with subtle introductions of pond water to the floating bag/bowl until both water temps are as near the same as possible.) NOTE: if you heat the tank above 78-80 degrees any deep coloured koi (Go-Sanke) will lose their colours....red to pink, white to flesh and black to mottled grey.
but your going to be looking at a large tank. mine is large in terms of water volume but not length. a 4x2x2 is not long enough really.

a 5 foot or 6 footer is more ideal i think. then you will be able to have a few of them growing up with some monster filters.