Aggresive Pond Fish !!!!

[Elderly]

I've successfully kept a miscellany of ordinary goldfish type fish in an outside pond
for many many years.
Sometimes I've noticed a bit of ganging up on a particular fish but it soon stops.

However in the last two or three days there has been a lot of VERY aggressive behaviour and each morning I've found one or two of the fish that have been chased dead!

I've done nothing different in terms of filter cleaning, feeding, the occasional partial water change etc.

Any ideas please?

[Elderly]

I don't know what they are, I inherited their ancestors 18 years ago from a neighbour
who was going to fill in their pond for fear of drowning their toddlers!

They appear to be ordinary goldfish although some are white;
no new species have ever been introduced to the pond and they've mainly
got on before.

Mating maybe ...... but killing (unless there are loads of males and very few females?)
It's quite distressing to see

[Elderly]

Mr GrimNasty said:

It's definitely spawning time, and not unusual for goldfish to die of exhaustion .... or appear dead (catatonic).

Not much you can do really .......

And make sure fish are actually dead before you bin them.

Thanks for the info but it's still GrimNasty to watch ;-).

I'm pretty sure that they were dead but if not they are now;
I put them into a nearby large natural pond where I often see a heron ...
... who will 'recycle' them!

[Elderly]

My pond has been calm for the last two days ...... fins crossed!

[Elderly]

Mr GrimNasty said:

occasionally they have a second go later in the year, but not often.

If you have Herons in the area is your pond netted? If not I'm amazed you have any fish left.

Yep - pond is netted and not only to guard against the heron:



How long is the gestation period? I've only ever seen fry in iirc November
and I assumed (wrongly) that they wouldn't survive the winter.

[Elderly]

I spoke too soon, they are at it again this morning .

[Elderly]

So I Left last night's attacked fish in until this morning to make sure that
it was truly dead and not in some kind of catatonic state.

This is what I found!!!!!!!!





I had NO idea that Water Beetles were carnivores.

Edited by Elderly on Wednesday 25th May 12:41

[Elderly]

Not the heron - in the past I have seen a nice neat slice taken out of a fish
which was due to the heron; we sometimes, but very rarely get a kingfisher too.

When there has been a heron attack in the past, the fish then stay down away from the surface for a couple of days.

They are definitely chasing one particular fish at a time,
it doesn't look like blind panic.

The white on the side of the fish in the picture is not an over-exposed image,
but looks like the side of the fish may have been scraped?

Water quality appears okay but the stuff caught in the filter is more strandy
than usual.

[Elderly]

It's too late for me to look, as it's now gone into the larger pond as pre-slaughtered heron fodder!