After having oxigen pump, filter , proper sunlight in my fish pond my 8 5inches koi carp fish died. ne reason?

Question

i dono da reason why dat hapen can any bdy help me sugstin a reason 4 dat?

Answer 1

your pond probably is not deep enough with direct sunlight the pond water temperature could be to hot for your small kois to handle

Answer 2

There are a bunch of reasons why your fish could have died.  I'll list them.

1.  You didn't feed them (not too likely.  I assume you fed your fish).

2.  The water was poisoned with raised chemical levels of ammonia, nitrite, or nitrate (very likely.  Koi are 'poopy' fish and very quickly soil their own water.  If the filter is inadequate for the water volume, they very quickly poison themselves with their own excrement).

3.  The water got too cold or hot. (pretty likely, especially if the pond was too small.  When you don't have enough water, it can change temperature too quickly and stress the fish)

4.  Something ate them, for example a heron. (not too likely.  You said they 'died' not 'were eaten')

5.  They had a disease (pretty likely.  Get a fish necropsy from your local vet to find out)

6.  A fertilizer or pesticide leached into your water because you didn't set your pond up right and rain runoff drains into it.  (not too likely as long as you have a proper pond liner)

7.  Someone murdered them when you weren't looking.  (not too likely, unless someone really hates you)

8.  They attacked each other.  (not likely at all; koi live together just fine)

Those are all the reasons I can think of.  The only way for you to know for sure, though, is for you to take one of your koi's dead body to a vet and ask them to perform a necropsy.  That's like an autopsy, but on an animal.  Call ahead first, since it's probably not polite to surprise a veterinarian with a stinky dead fish.  But yeah, totally have a necropsy done.  They're not too expensive and you'll finally know what killed your fish.