its only been a few days. koi get stressed when put in new environments. Just do your best to keep the water good. If they are swimming normally and aren't lethargic, or flashing and you don't see any ulcers or swelling, then I am sure they are just stressed a bit.

btw, you should really by yourself a test kit. since this is a new pond the bio filter has barely begin to cycle and you WILL have an ammonia spike followed by a nitrite spike. this is normal as the filter cycles, but needs to be monitored daily until the cycle is complete so you can make the necessary adjustments to the water to prevent the koi from getting sick.

basically when you test ammonia you need to add an ammonia binder and when you test nitrites then you need to add salt (1.5 pounds per 100 gallons)

Thanks Alot for the advice!! Im new to this koi pond thing so bare with me. I have a saltwater tank and the testing kit i have for it can also be used for freshwater and I was told that I can use it. Also should i change the water to avoid the spikes?? I have treated the water with two things: TetraPond AquaSafe water conditioner and TetraPond AQUA-ZYME. For the aquazyme, it says it reduces ammonia, sludge and organic debris and establishes healthy pond balance. Is the aquazyme considered an ammonia binder?? Also I was told to add pond salt, do i add it when the nitrate spikes or should i just add it regardless of the spike.

never used aquazyme before so I can't say. but in general I stay away from tetra products.

yes, you can and should do water changes to control ammonia, nitrites and in general maintian good water quality. 15-20% weekly is usually a good minimum, but if you are having trouble keeping things right you can do as much as 25% daily if you want...just don't forget to dechlor and be careful you don't drop the water temp too much.

my favorite dechlor is Chloram-X because it also is an excellent ammonia binder. Chloram-x dry is cheaper per gallon treated. Amquel is also a good brand.

with salt, its only really needed when nitrites show up. 1.5 pounds per 100 gallons. Keep the salt at .15% until the nitrites are gone. salt will not evaporate or dissipate...it can only be removed with water changes. If you want to maintain salt levels in the pond at .1% you can, but it really doesn't do a lot of good and over time can have a negative impact on the health of your koi.

Good advice I wish I had before I killed two of my koi.. 500 gallon pond though seems a bit small to keep koi though, any chance of increasing it to 1500 gallons??

Exactally my thoughts! 500gals is too small for Koi! Good for shubunkin and goldfish, pool comits, etc. But with Koi, you will begin to struggle to keep it clean after a couple years...they get real big and poop a lot!!

500 gallons is ok for 3 koi. They will not get very big in that pond, probably never more then 14 or 15 inches. Often called Bonzai Koi. The amount of waste produced is a direct ratio to the volume and quality of food that is fed. As for keeping it clean, the number of gallons is not as important as the size of the filter.

Of course a larger pond is prefered so the koi can be fed more and have room to grow to their fullest potential. Also, in smaller pond they won't get as much excercise and can lose their shape. they tend to have skinny tails and large bellies.

In Japan, bonzai koi are gaining popularity. Many urban dwellers in Japan do not have the land for a pond so the breeders have been raising bonzai koi. They are intentionally kept small by raising them in smaller ponds. These koi do very well at shows in the smaller size categories because they are older and more finished then the other fish in the same category.

I have a indoor 125 gallon pond with two Koi. Both very healthy. Water changed three times a week. They will be Bonzai Koi.They live with a lion head goldfish, 4 Gouramis, 1 Bala Shark, 2 long skirted small tetras . All get along fine all are healthy. Now back to what I wanted to say. I have a long skirted Tetra that did not eat for a month. Have a few plants in the pond so I thought maybe she was eating some of those. Never saw her though. She is on the skinny side. Did not seem to be sick, not hiding, swimming with the others. I only use salt if my fish get sick. I have never had success with antibiotics ( do not reach for over the counter meds at all) (If it is the fishes time to pass on I let them) (For me this has been rare once fish established). All the fish died when I use to reach for antibiotics. Now I keep clean water and do water tests. I do keep a jungle food antibiotic on hand for those still eating ( fish has to eat pellet, so if not eating then it is up to fate). Right now I never keep salt in the water. Only use it when sickness is found, and only in a small 10 gallon pond that works as a quarantine exception would be if ich was found in the main pond or more than one fish sick. Amount I use when sickness is in pond is 2% to 3% salt which is 2 tablespoons per 5 gallons or 3 tablespoons per 5 gallons. Today after one month the Tetra came up and ate some blood worms. Often the fish's immune systems heal them. I rarely have sickness. All my fish fed frozen foods, greens, and oranges , etc....
Fish have a real slow metabolism and can go a long time without food. If your fish is not hiding out, swimming with the others, acting normal, then why fill it with a lot of chemicals. Let nature do its thing. I usually just keep my eye on it.