HELP!!!! Fish death


Old 02-22-08, 03:04 PM
Thread Starter
Join Date: Feb 2008
Posts: 1
Exclamation HELP!!!! Fish death

I put in a small pond last summer and had plants and goldfish happily living together all winter. The plants died but provided cover for my fish so I left it until after our last freeze. We have been having warmer weather so I decided to "clean out" to pond and I removed all the dead foliage and scooped up as much algea as I could. Cleaned my filter, all is well. That was Sunday. By Tuesday 3 of my goldfish were dead and today my koi was also dead. What gives? Was I just too disruptive to them? I added no chemicals or fresh water. Simply scooped up the dead stuff....They lived through a semi-frozen winter and just die after I clean their home.....Any suggestions?

Oh, By the way, I tested my water and it all came out good. Ph normal, no ammonia, nitrates or nitrites!

Thanks! Leslie

Last edited by NurseLeslie; 02-23-08 at 08:52 AM. Reason: add info
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Old 02-23-08, 04:58 PM
Join Date: Feb 2008
Posts: 82
Same thing

Oddly enough the same thing happened to us. I have no idea what it was. The original fish had lived there for years. We replaced the same ones with new coy and goldfish and they died too. The pond is 800 gallons, has a filter and waterfall and plants.

Old 02-26-08, 11:15 AM
Join Date: Oct 2000
Posts: 674
Sorry to hear about your fish.

Considering the good test results for ammonia and nitrite, I think perhaps you had a case of hydrogen sulfide poisoning and oxygen deprivation.

This can result from the excessive organic decomposition. Perhaps while you were cleaning deadly amounts were released in the water when the buildup was disturbed.
Old 02-28-08, 10:54 AM
Join Date: Feb 2008
Posts: 2

Basically, I would argue that a properly constructed pond would mimic what God did in nature, using lots of surface area for beneficial bacteria, and needs to have a balance of living plants aquatic creatures (fish) and oxygenation, then no filter is required, no chemicals or UV sterilizers etc. They just need good surface skimming and a waterfall.

When you clean it once per year usually take some of the water into containers big enough to hold your fish, transfer the fish pump out the pond remove the organic matter (In the ponds I've built as above there is very little algae -the fish eat it). Add clean chlorine free water put the fish in the containers back into the water and after about 1/2 hour or so release the fish into the pond.

And then your good till next year.

Old 02-28-08, 12:59 PM
Join Date: Feb 2008
Posts: 82


Thanks for the article. I think that it told us exactly what happened and we are going to take steps to remedy the situation.

Old 04-05-08, 11:32 AM
Join Date: Jun 2007
Posts: 6
Now think about what happens if you or a fish are suddenly deprived of oxygen... would you or the fish survive for two or three days? I sort of doubt it. Since hydrogen sulfide is a gas, I think Leslie would have smelled it when she was stirring up the water while cleaning out the pond. We all know what rotten eggs smell like so I think we can rule this out too.

Modela, thanks for sharing your experience. It sounds like your problem is pretty common.

What may be happening here is Leslie and Modela were aggressive about cleaning their ponds and stirred up most of the bottom sediments that may harbor bacterial pathogens. Instead of stirring up all of the bottom at once, try cleaning off a small section at a time. Pathogens will still be released but not nearly as many and usually not enough to overwhelm the fish. Also, when coming out of winter cold water, the fish are at a weak point and not as able to fight off infection as well as after they begin actively feeding.

Start your spring cleaning by doing nothing more than aerating your water without disturbing the sediments. Use a pump or a bubbler to get the water moving. Well aerated water is not a good environment for anaerobic pathogens so they will have a much harder time wiping your fish out. Be aware that an acute infection may not show physical signs in the fish.

Then wait for your fish to be up and feeding before tearing into a lot of your sediment clean out. If you fear the green monster of the spring algae bloom, then at least aerate your pond for a day or so before you launch the attack of the killer scrub brush. I would still wait for the fish to actively feeding. This signals that the fish are gaining strength and health after the stress of winter's cold water.

Siphoning the sediments out, instead of scraping them up, will cause the least disturbance to the pond and release fewer pathogens into the open water.

2008 by Fwizzard

In an earlier message on another thread I tried to credit an authority by linking to them, but got reprimanded for using a commercial link, so I don't know how to give proper credit here except to say you may find the same information by looking for a pond biologist. It looks like just the moderators are allowed to post a link. Good luck to you.

By the way, that advertorial by pondsolutions was not good. As usual they want to sell all sorts of junk to you instead of simply understanding the real problem, but that's life on the internet for you!


Last edited by FWizzard; 04-05-08 at 11:36 AM. Reason: cleaned up a couple fragments

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