fish dying

Catoosa, OK

We have a dilemma in our water garden. Our goldfish are dying, one by one, every few days I find another floating, we've lost over 10 in the last few weeks. This is a well established pond (about 8 yrs old, for 6 years it was a koi pond but I found homes for them), 3500 gal, the water quality is good, no new fish have been introduced (earlier in the spring I did), I have looked over the fish that have died and they look fine, I can't see anything wrong with them, other than they are dead. We have frogs, about 5 that live in the pond and they are fine, the plants are healthy. I'm at a loss, does anyone have any ideas of what might be going on?

Phoenix, AZ

Any rain that could have produced run off into the pond that carried contaminates? Anyone spraying insecticide in neighboring lawns?

Catoosa, OK

Nope, it's a raised pond (built into a deck about 4ft off the ground) and we live in the country, closest neighbor is over 500ft away. Although I'll have to check, husband sprayed insecticide a few weeks ago (our neighbors have a huge flea infestation and their dogs are always coming onto our property so my husband laid down a band of insecticide between their property and ours - with
6 dogs and cats, we don't dare risk any of those nasty critters), but he sprayed it around 300 ft from the pond and east, we rarely get wind from the east... No dead fish yesterday when I got home,
but we had one Sunday, I'll be expecting on today or tomorrow. ;-(

Ocoee (W. Orlando), FL(Zone 9b)

Do you by chance have a heavier than normal leaf drop? Are you possibly building up too much tannic acid from rotting leaves?

Phoenix, AZ

Hmmm is the pond "4ft above the deck" or "4ft above the ground even with the deck"? If even with the deck what ever you treated the deck with could be contaminating water?

springfield area, MO(Zone 5b)

she said it was 8 yrs old, any chems in the wood, would have caused problems long before now I would think?

Catoosa, OK

No heavier than normal leaf drop. And, hate to say it, we have not treated the deck at all and it's in need of some care. It's cedar, but there's no where where the wood touches the water. Last weekend I was thinking, how nice it was, we hadn't had any dead fish for days, maybe it was over, then 2 dead over the weekend. They all act normal and look normal, until one starts floating. It's very frustrating.

Wells, TX(Zone 8b)

could some THING like an animal be killing them.. any teeth marks ?? I found dead fish before with teeth marks in them like after they killed it they realised they wouldnt eat it..

Catoosa, OK

Not that I noticed. I wondered about something killing them. We aren't losing as many lately, we go almost a week, and I start thinking maybe it's over, then bam, another dead one. This is so perplexing, I jokingly told my husband I was going to have an autopsy done on one... he wasn't amused. But it is driving me crazy.

Athens, PA

Is the deck relatively new? Are the fish dying after a rain? A lot of decking boards/pressure treated wood are treated with different chemicals and these chemicals can be toxic to fish.

Magnolia, TX(Zone 8b)

spring then fall, flukes hit, worms, treat them with, well drat, cant remember the stuff, have to figure out where i put my books

Athens, PA

Fish will typically jump with flukes....

Have you taken a scraping from the the skin of your fish and looked under the microscope?

Catoosa, OK

No, to skin scraping. They are now down to dying about 1/wk.

Deck is 10 yrs old, cedar, pond is about 8yrs old, and it hasn't rained here in weeks.

The last one that died I looked him over very closely (not microscopically though) and he
looked fine.

springfield area, MO(Zone 5b)

Could you have a plant in the area that is dropping now that it is fall, and maybe poisoning them? Have you tried a large water change?

Catoosa, OK

Actually, the dying started in late August, that's when a lot were dying, but then it started slowing down to about 1/ wk. We have now gone about 10 days with no floaters... Got my fingers crossed.
maybe some chemical got in, although I have no idea how it could since we hadn't used any.

springfield area, MO(Zone 5b)

do you have any neighbor kids that may have tossed in who knows what?
Or something that may have fell in, and died?
Have you been using a new feed?

Has your county, or city made any changes to the water (or maybe there is something else wrong w the water)
Maybe the street dept came by and sprayed ? along the street or alley or something like that and spray drifted?

Hollywood, CA(Zone 9b)

I had a similar problem last year and I spoke to a Koi pond expert and he said it sound like one or both of two problems. I treated for both at the same time so not sure which one it was but no problems since. The two problems were: 1. Not enough oxygen in the water, especially during the warm months when the water heats up and holds less O2. So I increased the volume of the water circulation. 2. Was the amount of sludge on the bottom of the pond. I had about 2 inches of sludge. He said when this gets mixed up by the fish or other activity in can release dangerous amounts of ammonia and other toxins. I added a sludge reducer and now have only a thin film of sludge on the bottom.

PERTH, Australia

tepesridge, what's happened with your fish since your last post?

Catoosa, OK

haha, sorry, I got busy with seed planting and forgot to check in here. They have actually quit dying. We lost a few over the winter, but nothing for several months. Not sure what was/is going on. I don't think it's too low O2, since it didn't start until the temps dropped off, and in July we had many 100-112 days and they were fine. I don't think it's sludge as there's not much down there, but it never hurts to add a sludge reducer.

I live in the country so no worry about a street dept ;-) and fortunately our water is really great (our water company sends out bimonthly reports reporting the water chemistry (which I love - I'm a geochemist ;-)). I am still checking on them (and it is possible we've lost some and they never surfaced, we have a lot of oxygenating plants on the bottom to hide bodies). Even though it has seemed to stop, it is still driving me crazy as to what was happening. Thanks for all the ideas!

(Mary) Anchorage, AK(Zone 4b)

A friend got all his fish through our winter in good health (he thought) which is not a small thing with our winters. Then in the spring they all died one by one. He felt it was some sort of infection that attached the fish when they were weakened by the long winter. There are good general meds you can add on a 'just in case' basis when no other cause of death presents itself. Just an idea. Maybe you only lost the weakened fish.

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