Hi I am new to this forum and pretty new to looking after koi. we have had a pond for a couple of years and have just made it larger so needed to buy some new fish. we made a big mistake of buying a koi from a bargain bucket which i think i am now going to regret. it is doitsu about 10 inches . when we first put it in the qtank it it was not feeding sat on the bottom with fins clamped. I read up on this and thought it must have parasites so we gave it a salt bath then after let it recover in a plain water tank and then later treated it with malachite and formalin. This seemed to do the trick when it went back in the qtank it started swimming around and feeding well we left it here for another couple of weeks then noticed it had fin rot on its tail so i treated the tank for 5 days with a fin rot treatment. the fish seemed fine was swimming and feeding well so we decided to transfer to the new big pond. after catching it and floating it in a bag we could really examine it and saw what looked like a row of worm like protriusions underneath the fish symmetrical . on looking closer we realised that it was its ribs poking through. I really dont know what to do has anyone else heard of this and is there anything we can do to help the fish .or is it kinder to euthanise it.
Any siggestions would be graetfully recieved
