Newish pond with new fish

[bramd]

I have a 6000 l concrete pond, which was build last year summer.
This april I have added 10 small blue orfes. Only two were swimming around, the other 8 have always been on the bottom.
Since a few days, one fish seems to be dieing every night.
Attached is a picture of the most recent dead fish, It seems to have small wounds in two places.
Any idea what could be the problem ?

Air temps ranged from 8c at night to 24c daytime.
The water is clear, Ph in the morning is 7, in the evening 9. Gh (7) and Kh (9) were low, so I have added Maerl to the water.
The pond has a 900/h airpump running constantly and a decent number of oxygen plants.

 

[MitchM]

Welcome!
If you are referring to the red patches as wounds, it may be a bacterial infection.
Did you cycle your pond before adding fish?
Which Maerl product did you use?
It could be helpful if you could include a picture of the whole pond.

 

[Lisak1]

Welcome @bramd !

@MitchM is a good one to help with water quality - and I'll second the request for photos of the whole pond. Like Mitch, I'm wondering if you added the fish before the pond had a chance to cycle.

 

[addy1]

Welcome to our forum!
Mitch is our water expert! He can help you understand what has happened.

 

[MitchM]

You guys are too kind.
There's a cheque in the mail to you for $5 each.
(as per previous arrangement)

 

[Lisak1]

You guys are too kind.
There's a cheque in the mail to you for $5 each.
(as per previous arrangement)

Thanks! Just a few hundred more glowing endorsements and I can buy that weather station! (Just don't send me any of that Canadian money!)

 

[j.w]

@bramd