Originally Posted by ogawa only

Hi snowman ,

it's fairly easy to answer what is wrong with the fish , its got a fin/skin rot based bacteria infection , the same type of bacteria that cause ulcers .

but for how it got it we would have to thoroughly investigate your pond !!

the reason why i say this , is bacterial problems always have a starting cause , but how they get to the fish them selves , is another question !!


so lets look at the bacteria , in any pond system , there are good abd bad bacteria , usually the good bacteria out number the bad , as you filter usually sheds bacteria into the pond out competing the bad .

so now we go through what lets bad bacteria take over :
a dirty pond , ie a build up of waste on bottom , which turns to the black muddy stuff .

build up of waste in the filter , same as above .

dead spots in the pond or filter (no or low oxygen spots ) this includes pipe work .

also if your filter is constantly playing catch up , and dirty media . also plants and the pot substrate they sit in .


now this as a whole , is not the reason how the fish get infected , but is just a means on how the bad bacteria can manifest in your pond .

now for the fish and how they can get infected :

1st would be fluctuating pond parameters , especially nitrite .

2nd and this is one of the biggest IMO , parasites , as they attack the koi and usually leave tiny lesions in the skin , and mucus , giving bad bacteria a way in !!

3rd bumps , scrapes and knocks .

now to find out how the story unfolded in your pond , you need to do full water test's 2-3 times a day for a couple of days using you usually daily activities on your pond , like feeding ect , so a reading showing as close as possible the norm .

secondly , go through your pond with a fine tooth comb , check every thing you can think of , and make a list of what could be cleaned or cleaner .

thirdly , get a scrape done , or do one yourself , as its always best practise to do a scrape before any treatments .
The reason we say this , is , if you have a bacteria problem in the pond , but parasites are the trigger , ie breaking down the fishes mucus or immune barrier , then it would be best to kill the middle man , then sort out the bacteria problem after the parasites .

steve