Tips in buying Koi
Things to consider for having koi as a pet
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Pond location you must find the best site for your koi pond.
Check Available Cash
Determine the material of the pond
The number of koi you intended to keep
Then decide on the width, depth and the shape of your pond.
Then choose a good filter and aeration
Where to buy koi? In buying koi always try to buy your fish from a local supplier to lessen the stress of the koi.  Examine the premises carefully.  Do they look clean and well managed?  Are the tanks free from dirt and well filtered? Watch how the dealer catches and handle the fish, because rough treatment will damage the fish and it causes stress for the fish.
After finding a good dealer we now go to choosing your koi.  Choose the one you like not what the dealer or others think its nice.  Because its your collection and you are the one will enjoy it in the future.
After finding the type of koi you liker. Poin to check in buying koi.  The stock should look active bright eye, and should response immediately to feeeding.  Fish sulking on the bottom of the pond with clamped fins are sure sign of trouble.
After choosing your fish and put in a plastic make one more check for any signs of parasites, blemishes, missing scales, clamped or diseased fins and sunken eyes.  The gills should lie close to the head and should not stand out.  The body should be rounded but not bloated. Avoid fish which has scales standing out from the body this is certain indication of dropsy.  Never buy an ulcerated fish and do not purchase any other fish from the premises as the rest are probably incubating this bacterial infection.
After buying your koi quarantined it to make sure it is disease free. If you don't have a quarantine tank you can use a large basin or aquarium will do but make sure it got an aeration and filter.  Quarantine it for 3 weeks to 40 days.