Question
My new pond is approx 8 weeks old and I had 6 fish from my old pond and two are Golden Orf nearly 5 years old. On Saturday I found recently added fish 1x shubunkin and 1 x Yellow comet dead upside at bottom of pond.  I noticed the other small yellow comet has a lump on his side which looks like fungus (floaty white bits) Have treated pond with Tetrapond Medifin.   At 7am today I noticed one of G. Orf upside down at the bottom of pond, I netted and righted him, he swam away, bumped into the pump and went upside down again. I left him in the net in water which is supporting him, but he's rolling on his side.  Now he is lying very still, but when touched moves a little.  Please can you help, can I save him and the others.  Am very new to pond keeping. My first project was a little pond and they all survived for 5 years with no proper filtration. I now have Oase Biofilter system and pump....Help


Answer
I'm sorry about your fish.  When fish have trouble swimming and are lethargic, it could be almost anything including parasites, bacteria, funguses, viruses, water quality, poisoning (chlorine, ammonia, nitrite, pesticides, etc.), low oxygen, and more.  To narrow it down, I have some more questions.

How big was your old pond?  How big is your new pond?  How big are the orfe?  Have you tested the pond water for pH, hardness, alkalinity, chlorine, oxygen, ammonia, nitrite, and nitrate?  If not, try to do so. Did you add anything to the water?  If you have city water, you should add dechlorinator.  I also suggest some pond salt at 0.05%.  Did you quarantine the new fish?  If not, they could have brought something into the pond (it sounds like the comet brought in fungus).  Do any of the following have contact with your pond water - fresh mulch, runoff from treated lawns, concrete, mortar, cinder blocks, limestone, etc.?  Various things can leach into the pond water and cause problems.  

Sometimes we don't know why our fish died. I lost a little goldfish yesterday and don't know why.  I suggest doing the water tests, doing a partial water change (add dechlorinator), and perhaps treating the fish with antibiotics and antifungals.  You did see what seemed to be fungus on one goldfish and have already treated for that so that should help with that problem.  It's hard to say if that's the only reason that the orfe is sick or not.  The fungus could be fungus or perhaps something else since I didn't see it and can't give my opinion.  Sometimes bacterial problems or skin sloughing look like fungus.  Orfe are sensitive to many "medications" so the Medifin for the fungus may harm the orfe (perhaps in addition to the fungus itself).  It can be a gamble to use harsh medications.  Do we let the fish die from the fungus or from the "medication" to treat the fungus?  If you want to remove the fungal medication from the pond, do water changes and add fresh carbon to the filter in a mesh bag.  My head is spinning trying to sort this out for you.  You can see there's no easy answer.  I would probably say that if you definitely see the fungus, try treating with the fungal medication at half the dose.  If the fish don't show poor signs as a result, try the full dose again.  If you don't see fungus any longer, then just treat with pond salt and maybe some MelaFix for now.  Things in the pond have a way of sorting themselves out.  It's unfortunate that a few fish will die along the way.

Good luck!

Robyn
fishpondinfo.com