Disappearing fish

[Clarepp]

My ex partner has twice stocked our natural spring, stream and pond with a variety of goldfish and small koi, approx 120 each time about 8 months ago they disappeared overnight, he then put up stakes and 3 rows of fishing wire approx 1 ft high, a mammoth tax, he left me in Jan so I have been left to care for all these fish, sadly over night last week all disappeared again… today I have discovered this one fish that seems to have reappeared with injuries on its back looking like bite marks… what do you think has caused it and how do I care for this poor fish? First image shows the injured fish the second image shows some of the fish swimming upstream, for so many fish to disappear in less than 24 hours, and the water not being churned up from the silt at the bottom (as it’s a natural spring formed stream and pond) please help

 

[jgrandmont]

If it happened here in the US, I'd put my money on it being a heron. Last summer, we lost two large sarassa goldfish from our pond and another large goldfish was injured. The injured one healed up nicely without any intervention. We didn't see the actual attack but are guessing it was a heron that was able to get a good view of the pond after we took down a large nearby maple tree. Are there herons around where you live in Britain?

 

[j.w]

@Clarepp
Sounds like you need a net up higher so the bird can't poke your fish and kill them. I have one above mine about 4ft high so I can lift the side of the net up so I can enter if needed. How big is the pond?

 

[rothenbj]

I had a couple disappear about 5 days ago, one a beautiful koi and the other a white comet. I'm afraid the herons have again found my pond which they did ten years ago but I've seen no change in the population since.

 

[j.w]

@rothenbj
Might be time for a net?