I recently bought koi from my petstore. My koi are not growing!?

Question

I brought the koi home and put them in my aquarium. They seem happy and active but they are not growing. When I went back to the petstore i noticed that the other koi in the tanks had grown quite big about duble the size as my koi and when i first saw them. I don't know why my koi are not growing. They are from the same batch as in the pet store.

The tank is big bigger than the petstrore's tank. But i don't really change the water and it is about 50-60 gallons. I jus have 2 fantail goldfish, 2 angelfish, 2 mollies, 2 swordtails, 2 scavengers

Answer 1

you have a worringly odd mix in your tank.
take the koi back to the store, unless you have a 1000 gallon koi pond in your back garden? a koi, depending on species, will grow to between 2-4ft long. larger has been heard of! they are carp, related to goldfish, but closer related to carp than a goldfish is.

what do you want this tank to be? you are currently mixing tropical and coldwater fish, this is a BIG nono. i would get rehome your fantails too (they need a 30 gallon tank just for them). and turn your tank just to tropical. with the angels, mollies and swordtails.

what are your scavengers? all fish that "scavenge" will need their own supplementary food. what are they? corys? loaches? plecs? an ID is essential for any fish you have in your tank.

Answer 2

Its because your tank is overstocked and most importantly you don't change the water. Fish release a hormone into the water and if not taken out during weekly water changes it causes them to stunt, like yours are doing. Koi are pond fish and shouldn't even be in a tank but if you would like them to grow then start doing water changes at least once a week and at least 30% of the water each time. Just remember that koi can get up to 3 feet long and goldfish depending on the type can get anywhere from 8-18 inches long.

Answer 3

As you know, koi are pond fish and require 1 sq. foot of SURFACE water per inch of fish. Koi DO NOT quit growing due to the size of their tank, however they will grow slower. How large is your tank? 10 gallon for two koi or more is NOT ENOUGH. You may see small ones in the petstore that way only because they are not there very long.

Also, they are cold water fish. Warm water will also retard their growth.

What are you feeding them? Koi pellets, peas or lettuce are best for your fish. A color enhanced food will also help.

If you recently purchased these fish, how recent was it and how quickly are you expecting them to grow? Perhaps the fish in the store are new fish of a different size. Koi will not double in size even in a month.

Are you positive they are from the same batch?

Answer 4

Do you test your water? Is your tank cycled? This comes down to water quality, not size of environment. With poor water quality, your koi will become stunted and die, while the store probably has a system where the tank is not only cycled but does a 24 hour water change. This is why stores can overstock their tanks. Their filtration systems are far superior. People with home aquariums can set up systems almost as good, but not exactly like those.

Answer 5

Your aquarium isn't large enough for the number of fish you have in it. A 'koi' is just a goldfish ... and the 'grow' to fit whatever it is they're put in ... if you want your koi to grow, you'll need to get a 'much bigger tank' for them ... and when they've 'stopped growing' it will be time to move them to a bigger tank again, until they've reached 'full size' ... which can be as large as two to three feet long.

Answer 6

how big is your tank?
koi are meant for ponds
so it should be at least 150 gallons or 100 at the least
if its under this and you expect them to grow...
good luck
or go back and ask

Answer 7

Fish grow to fit the size of the container they are in. The tank at the pet store is probably bigger than the one you have at home. Buy a larger tank!