Advice needed.

Wow what great pictures of those worms! And the fact that the fish was doitsu (essentially scale-less) allowed you to pull the worms with the heads intact! I value the pictures highly. So, with those worms diagnosed (ANCHOR WORMS – lernea elegans) we know the fish have actuallly HAD the baby versions of the worms chewing on them for about a week leading up to the appearance of the adults. It can also be assumed that other parasites are present.
All parasites can be stressful and cause fish to be lethargic. Even die. It’s CRUCIAL to note the color / condition of the gills of any fish that has IMMEDIATELY died, because the gills are kind of the window to the soul. Parasites (and those worms) can attach to gills and the fish are essentially oozing a tiny amount of blood from the sensitive gill tissue the whole time. And worse, bacterial infections can set in.
If the pond is 80 degrees or higher, Koi Herpes Virus isn’t happening. So you win. Maybe in Sri Lanka, the water’s toasty. If the water IS that warm, make sure aeration is highly sustained.
I would recommend a 50% or so, water change. That gives you a reduction in the salt, residue from Potassium permanganate, a thinning of the herd as far as ciliates (they hate fresh new water*) and then you can safely use a formalin/malachite combo. The reason you can use Formalin/Malachite so well after a large water change like that, is because you will have cooled the pond a little. Cooler water = safer formalin. Daily x 3 days then skip a day, dose and then skip a day and do a fifth dose. Done.
Water under 78 degrees F – – and high aeration. Dosing daily breaks the ciliate life cycle. Dosing every other day at the end intercepts Flukes. You need anchor worm treatment for the Anchor Worms. Formalin is ineffective.
*fresh new water. When I’m holding a fish health lab, we are strict about using more than 30-40% new water with the sickies, because new, fresh water seriously diminshes the parasite burden on the fish which we depend on finding for teaching purposes. Use this little factoid.
Here’s a link to what you need: Formalin Malachite: “Microbe-Lift BSDT” Anchor Worm remedy: “Microbe-Lift Lice & Anchor Worm”
Hopefully those links are easily clickable.
Remember – Water under 78 with high aeration!
And always: Test your water when in any doubt of the quality. pH is a biggie.
Doc Johnson

On Thu, Mar 28, 2019 at 3:04 AM Amila Sandaruwan Photography <> wrote:
> > Dear Dr. Erik Johnson , > > I am Amila from Sri Lanka. I recently came across your channel and I am > really proud of what you are doing. > I have a indoor pond. Couple of weeks ago I bought some carp fish. Now > half of the fish are dead including the two big carps I already had in the > pond. > A Week ago I put Potassium Permanganate 3 times in the pond with lot of > oxygen. After that they were alright for few days. I found some kind of > parasite like worm on the body (attached to belly/ tail ) of a dead carp > and I gave “Levamisole hydrochloride + Fish oil ” with the food for 2 days > for the rest of them. They were ok after that. > > After two weeks I bought some more fish (bigger ones – carps). > Now I see rest of the old ones are having the same symptoms, they are > floating in the water. > > *Up to now I have not made any water changes too.* > *Everyone seems to enjoy to sit in the corner of the pond. * > New big ones are active for food. Today I put 2kg of salt too. > > Could you please tell me some treatment, at least to save new carps, > Should I separate the old ones from new ones ? How should I continue the > treatment ? > > thanks & regards, > Amila >