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?

[Big Al.]

What types of fish are you keeping, I'm assuming that the dead fish are the same species as the ones ganging up and chasing.

Don't forget we are entering the fish breeding season.

[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

[Turn7]

If you think pond fish can be aggressive, try keeping African Rift Cichlids.......

I think Al has hit the nail on the head with breeding.

Its possible the population has increased naturally to a point that the aggression has to be stepped up by the Dom males.

[Mr GrimNasty]

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

Not much you can do really other than try to make sure there is enough cover for fish to escape over enthusiastic males at the same time as not allowing them to get cornered - which is a bit contradictory!

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

[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!

[anonymous-user]

Turn7 said:

If you think pond fish can be aggressive, try keeping African Rift Cichlids.......

My tank of african cichlids had more scandal then any soap opera.

Affairs, Incest, Violence, Murder, Infanticide, Inter-species shagging, were a daily occurrence.

[Elderly]

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

[Mr GrimNasty]

Spawning is usually short lived, 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.

[Poisson96]

Vandenberg said:

My tank of african cichlids had more scandal then any soap opera.

Affairs, Incest, Violence, Murder, Infanticide, Inter-species shagging, were a daily occurrence.

My Endlers in one there, except violence. Murder was by all my fish ganging up on a rather large loach,

[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.

[Mr GrimNasty]

Very temperature dependent, probably 4-8 days, then a few days absorbing the sac, but unless you got right down to the water surface and have good eyes and knew what to look for you probably won't notice then until late/summer autumn. Most often first notice them sunbathing in a gap the weed.

If you pull out a few bits of weed where they were thrashing about, you might see tiny individual blobs of jelly which are the eggs.

[Turn7]

Vandenberg said:

Turn7 said:

If you think pond fish can be aggressive, try keeping African Rift Cichlids.......

My tank of african cichlids had more scandal then any soap opera.

Affairs, Incest, Violence, Murder, Infanticide, Inter-species shagging, were a daily occurrence.

Indeed....

Exactly why I love them!

[Elderly]

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

[Big Al.]

It's all part of nature, Rivers in the UK have a closed season March until June 16th it was originally introduced as the "breeding season" and to give fish a chance to recover during breeding and recovery.
I've seen some fairly extensive wounds on fish that have suffered from the exploits of breeding. I't also ensures that only the strong survive, to pass on those genes to the next generation.

Ain't nature wonderful, albeit somewhat cruel at times.

[boobles]

I find this with one of my fish, it seems to chase one other fish & completely leave the rest alone. I have often wondered why this is.

[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

[rev-erend]

You see this a lot in tropical tank fish.

Male Guppies can chase the females to death sometimes.

Perhaps you need a few pike in there to give the males more to think about than breeding

Edited by rev-erend on Wednesday 25th May 15:59

[Mr GrimNasty]

It's very odd you are getting so many dead, are you sure something else isn't killing them and that the 'aggression' isn't panic?

Great Diving Beetles can certainly kill small fish - but I don't know how big a fish they would tackle, and Herons would be quite capable of killing a fish through your net - stab wounds or missing chunks or scales would be the giveaway in that case.

[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.