Pond fish death - heron or accident ?

[Kr1stina]

We are inexperienced fish owners and have 9 goldfish and 3 koi in a large pond in the garden. We've had them for two years and haven't had any trouble with herons as the pond is deep .

Yesterday I found the largest koi , which is about 10" long , dead on the slabs at the side of the pond . It had obviously been there for a few hours and had been nibbled by the garden birds ( we have a lot).

Is this definitely a heron or could it have jumped out and got stranded? All the other fish are fine , they don't seem spooked . The dead fish has been nibbled at rather than spiked or slashed ( sorry ) . We've never seen a heron here or in the area .

I thought that herons took the fish away?

We have several small birds of prey in the area , sparrowhawks I think . But do they take fish ? They've killed a few wood pigeons .

I know that heron precautions are expensive and ugly, so I don't want to do it if it's unnecessary .

Any advice appreciated .

Koi will jump out themselves if there is a problem...water quality is a big issue but another fish chasing it could cause it to leap out.

Thank you Matt , that's interesting . Although the one that died is easily the biggest fish in the pond

Do the koi get annoyed when the goldfish chase them? I can see that one in particular is very annoying, although they have not been doing much spawning behaviour yet, I think because it's been unseasonally cold .

Do I need to check the water ? We've just cleaned the filter so it's not the clearest but should be OK by tomorrow .

Any other signs of fish unhappiness I should look for ?

When your say you cleaned the filter can you describe exactly how you did it?

If you have no islands on the pond a single piece of wire running around the perimeter of the pond at about 10 inches high can deter herons from getting close to the edge and fishing. It's not 100% effective but is cheap and less unsightly than netting.

Herons usually either take the fish whole, or if they miss, the fish are injures with either stab wounds or scrape marks on both sides. Once they've found a spot, they also tend to return.
Are your other fish lurking at the bottom instead of coming to be fed? That's another clue that it might have been a heron.

Re filter - DH does it so I will ask him when he wakes up ! I know it an Oase filter and it's cleaned by running the water back though it and it's pumped out into a drain .

We have no islands and the edge is slabbed ( it's a formal pond ) so we could fairly easily fix a wire. I've been put off netting after watching a video on you tube of a heron walking all over it .

We have no shallow bits for a heron to stand in, the pond is 900 deep. We thought that's why had not had any trouble so far .

Re dead fish - there are no scrape or stab marks at all . It's just been nibbled, i assume by the small garden birds . I took a photo , should I post it or it that too gross ?

The other fish are acting totally normally , coming up for food .

I'm in the garden a lot , as gardening is my main hobby and I've NEVER seen a heron. Not just in our garden, but in our village .

I know more about herons and goldfish than koi, and it sounds less likely that it was a heron to me. You'll get better advice when the koi people wake up.
I'm sorry about your fish, whatever the cause. I'm very attached to mine, even though they are just fairground and rescue goldfish descendants.

Our three local herons live between 3 and 5 miles away, they are good fliers and will travel further for a good feast.

DH says he just back flushed the filter . I think he's doing it correctly . It's the only thing he ever does in the garden.

We have quite a big pond and sometimes a fish will leap out of the pond. But they can't always find their way back, so unless you actually see them do this, you can't really stop that.
If you are concerned about the water you can buy little testing kits to test the ph levels etc.
Herons can be a pain, but usually they carry the fish off and drop it in someone's garden !

Ok no that sounds fine re the filter flushing. I was checking you weren't running it under chlorinated water or anything.

It does sound like a random jumping fish, but you don't say if you have a water testing kit. I'd recommend you get a liquid test kit for ammonia, nitrite, and nitrate.

Do you do water changes in the pond?

No we don't have a testing kit so I will get one .

we have a slow leak in the pond so are constantly running water into it. Not ideal I know but we have plenty rain, a high water table and no water meter !

Lin - do you manage to save your jumping fish ?

It depends if we happen to see it. One time we went to the fair in the evening. Went down the garden when we came home and saw a fish on the grass. Luckily it was raining slightly so the fish was ok. We have lost fish in other circumstances though, when a previous pump wasn't working correctly and we lost a lot of the biggest fish as the water became toxic, and the bigger the fish the more it affects it. We have several Japanese koi and a mix of other fish and all has been well for several years now. I have even had a beautiful koi in our bath filled with water and had to sit there for ages pulling it gently backwards and forwards so the the air got in his gills ! But we still have him ! Dh has just been cleaning his filter box and we often get one of the smaller fish in there or a frog ! They go through the pipe in the pond which leads to the filter. You do need to look after the pond but it dosent take that much work really. According to Dh ours is only 8000 gallons, so it is smaller than yours I think. Ps we get loads of horrible little red worms in the filter box, hence I will never be cleaning it out !!!

Oh and we also had a leak. For years actually and the hosepipe was on day and night running a trickle of water in ! We eventually had to get a new liner, this was despite laying carpenter directly onto the ground under the liner, so we guessed a stone made a hole !

Having a pond is one of the pleasures in life, nothing better than to just sit there and watch all the fish swimming around on a summers evening ! Especially with all the different colours.

Sounds like he could have jumped out I'm afraid.. I love koi, fancy sharing any photos of your pond and koi if you have any?

Here are a couple of my pond

Ah beautiful. Looks soo relaxing. Have you had anymore problems with your fish?

No we luckily haven't lost any for a while. ( touches wood ) pond is very healthy these days. Dh takes good care of it. Me. I just look at it ! I do love sitting in the garden in the evenings when it's warmer just listening to the waterfall. Those photos are from last year. My brother went to China not long ago and sent me a picture of all the Koi there, there are so many of them, they must of cost a fortune ! I will see if I can find the photo.

I wish we had all of these !

Thanks for asking buggers - no more problems with the fish. Just that one random koi . I am hoping you are all right and the silly thing just jumped out.

I didn't see you request for a photo until late last night, about 9:30 so it was nearly dark . Here's the pond but I couldn't get the fish to pose for a photo

If you constantly topping up the water then it could be that the chlorine levels are too high.

That's a swimming pool !! It looks lovely.

Thank you ! The kids do play in it when it's hot ( like this week ) . Surprisingly the fish don't seem to mind.