I have some fish in my quarantine pond and seemed to have messed up my bio filter by mistake when i set it up. Now, it has taken two weeks to get the water condition right again, in the meantime the poor fish had high nitirites, although I tried my best to do what I could.

Now all is well and the fish are active and really hungry (I didnt feed when the water was bad)

My problem is I have noticed over the last 2 days or so, some of the fish periodically scraping on the floor, which makes me think they have parasites starting. Today I am going to increase the salt to 3kg per 1000 lt. I am feeding garlic as well as there other food, but only started feeding again yesterday, so guess the garlic hasn't had time to help matters.

now I need to know -
Should I use a general medication for parasites to prevent any further infestation, or leave it and just monitor the situation. I would hate for things to get bad. If yes I should medicate, which one should I use? I dont have a microscope and dont have a clue why they are scraping. Also its not all of them, only seen 2 or 3 doing it.
I must also mention, apart from the scraping, they look good, no clamping fins, swimming normally, and only one has a bit of redness in the tail.
sorry this is so long.

If they are scraping, the possibility of parasites are quite big.

I can not advise a "blind" treatment. You have to establish if there are in fact parasites and what kind, because that will determine the type of treatment.

My advice is to either buy a microscope, use a friend's scope or ask a dealer to come and do a microscopic scrape.

Thank you Paul.

I think I will try the salt first and see how they go.
I have increased it to 4.5kg per 1000lt, and havenet seen any scraping but will watch them the next few days.

I saw this on your web (thanks) was most helpful.

Quote :

SALT

4kg of salt per 1000 liters. (Maximum 5kg per 1000 liters)

Salt bath: 1 kg per 45 liters for 10 minutes.

This will create a mucus coat to prevent the bacteria from attacking the fish and will throw most external parasites off the skin.

It acts as a disinfectant.

It kills 90% of parasites and bacteria.

It combats the effect of excessive water entering the koi causing pressure of kidney functions through it's wounds/ulcers(if any)

It lower the toxicity of Nitrite poisoning.

We believe that the average koi keeper should stay away from chemicals as long as possible and stick to the more natural safest ways of treatment, being salt.

Recommended first treatment if you suspect problems and you are unable to diagnose the specific problem.