Dead Fish

I have lost four fish this morning and another is just clinging to life, expect it to be dead when I get home.

I notice that I was loosing a lot of water the other day, the filer was full of sludge and the water was coming out of the top so I turned the filer pump off, other the other smaller fish are ok it's the very large Golden and Blue Orfe that have gone, I have had them for about ten years and bought them when they we about 2" long.

Also I have a lot of black sludge that sturs up when I take some of the oxy plants out when they get too big, it also collect in huge amounts in the filter, is it "fish Poo" or soil from plants that have tipped over?

My pond is about 15' x 6' x 2.5', I started with about 23 mixed fish, 5 Shabunkings, 3 Sarasa Comets, 1 Blue Orfe, 5 Golden Orfe, and various Gold Fish, they have all interbred so I have lots of gold ones with white bits and white with a bit of gold, do you think I have too many?

I know BM is a knowledgeable chap regarding ponds please help.

 

Hi suedobie, sorry to see your fish are suffering. Apart from the fact that they are dead, they look healthy to me. Sudden death in such numbers in my experience is almost always water quality related. Lack of oxygen or significantly high levels of nitrates from fish poo debris etc :( and it sounds like your filter may have pumped contaminants into the water ? If you have a flapping fish I would have him out in some pond/tap water mix in one of those storage tubs to see if he recovers. I have done this before and the tubs work well for holding fish while you carry out maintenance. It certainly sounds like the pond needs a de-sludge to re-allign the balance. Some sludge is good as the bacteria at the bottom aids filtration. If it were me I would reduce the sludge to an acceptable level with a water change perhaps 50%+ depending on how easy the sludge is to get to? adding a good quality water conditioner for ponds. I sometimes use a de-chlorinator/de-stress tonic but its been a while so I can't recommend one. Fairly routine stuff, but I think it is just a case of water quality

Another theory could be that the recent rain has washed something unpleasent into the pond ? If so the water change would be appropriate for this too.

Beautiful fish, have you got storage for the other fish so you can have a go at the pond.

I hope this is helpful. My main experience is with huge tanks and slightly different filtration to ponds. There are probably others on GC with a better insight into sudden death in outdoor pond fish. But I have lost big 2 feet catfish to a broken filter and the water quality being destabilised.

BM :(

 

sorry to hear about you losing your fish like this suedobie, I although havnt got a pond used to have a large tank full of lovely goldfish and lost them one by one i was very upset and i do feel for you. :(

 

Hi sue sorry about your lossI had a problem similar to this about a month ago but fortunately managed to save my fish my pond level had fallen and one evening I topped it up the following morning all the fish were gasping one was almost dead I have a wildlife pond and in desperation put this fish in I moved it until it came to and luckily its still alive in fact I can't catch it to put it back, It was definitely oxygen starvation stirring the pond up the previous evening had done it bear in mind also when you top up you should neutralise the chlorine or the fish get a double whammy, since this occurence I have installed a new filter and pump water now crystal clear I would go for a good clear out and work out how many fish you can support in your pond work on the formula of 1" of fish per square foot of water

 

Hi Suedobie
Sorry to hear of your fish dying :(
Some great advice from BM.
An inflatable kids pool would make a good temporary pond to house the fish.

Have you tested the water for ammonia and nitrates to rule it out?

As you said the filter had water flowing from the top, logically it has gradually become blocked by "sludge" which reduces the flow.
The nitrogen cycle can reverse in some circumstances which will convert nitrite back to ammonia...effectively a filter in reverse.

Assuming the filter was the correct size for the fish load to begin with, this gradual blocking has reduced it`s capacity over time and ammonia levels may have built up.

It seems your pond has about 1400 gallons at the most.
You gave the starting numbers of fish but it seems this may have increased (a lot?)

More fish = more filter, so it`s possible your fish population has outgrown the original filter.

Strangely, most pond filters are rated for pond volume.
The filter should be sized mainly by the fish load and not solely by pond volume.
The speed the water flows through the filter is very important, so you also have to size the pump and filter accordingly.

Here`s an example, If your pump is 1400 gallons per hour, the entire pond volume "may" go through the filter once an hour, but the water may pass through a small filter in just a few seconds.. too fast for the bacteria to do their job

Doubling the filter area, while keeping everything else the same, doubles the time the water spends in the filter and allows the bacteria more time to do their job.

If you go the other way and slow down the water flow at the pump, you will reduce the number of times the entire pond volume passes through the filter.

Good luck with the pond.

 

Thanks everyone for your advice.
The level of the pond had gone down by about 1 foot so I topped it up with tap water sprayed from a hose attachment above the pond to dissipate the clorine, I have done this manh tims before and had no ill effects.

The filter is an Oase Biotech 10, not sure of the volume it's capable of filtering but I have had it for about 10 year with no problems, also all the other (50 or so) smaller fish are all ok.

Where do you think the sludge comes from? is if Fish Poo?

I have held the fish in a childrens paddling pool before, while we were creating the new pond, the water went black but the fish were all ok, had a pump in it spouting water into the air for oxygen.

The last Big golden orfe was dead when I got home today.

My boss has a pond vacuum that I might ask if I can borrow to give it a good clean out.

Quite upset really about loosing the fish, I know they are not a respnsive as a cat or dog but having had them for so long I feel that I have let them down.

How long would thay have lived otherwise?

Sue

 

My experience is like BMs. Oxygen is the first requirement and it gets worse with rising temperature. Given the ponds are probably at their warmest now that might explain something. Usually the fish come to near the surface 'gasping' if they need more of it.

I'd avoid stirring the sludge at this time, but I would clean out that filter pronto, top up the pond (has a heron holed the liner?) with fresh water, and/or decant your fish elsewhere.

The little fish always seem to be the toughest!

 

The filter seems plenty big enough.
Surface agitation is better than a bunch of airstones to oxygenate water.
The cheapest way is to install a small fountain pump (economical to run) or perhaps your filter pump has excess capacity you could use?

Aside from improving the interface of air and water, it will also reduce the water temperature via evaporative cooling too, especially if you run it at night when it`s cooler.

Don`t forget to rinse out the filter medium in pond water..not tap water

 

Much of the sludge at the bottom is comprised of the same particles that make green water, mud washed into the pond from rain, dead insects etc. and as you say, fish poo.

I know what you mean BM, but I had to laugh. My grandad would have lived to be 100 if he hadn't died.

 

When I built my pond some years ago I put goldfish and golden orfe in, everthing was fine for a couple of years or so. The goldfish started to breed, and the numbers increased.
Then one warm night in late May my pump failed, in the morning it was terrible, the water was splashed everywhere, as the orfe had been jumping trying to get oxygen. The orfe were all dead, floating on the surface, the goldfish although gasping were still alive.
Orfe are not really suitable for small garden ponds as far as I'm concerned, I found out the hard way, they need more oxygen than carp.
I would never put orfe in my pond again.
Its about time these people that sell them gave more advise to those of us that are not really fish experts and took a more responsable approach to the subject.
I saw someone the other day buying alsorts of fish, one of which was a sturgeon of some kind, and no enquirery was made as to how big, or what type of pond the person was going to put them in.

 

I made the same mistake when stocking our small garden pond and put 2 small blue orfe in now they are about 8 inches long.The thing is we have become very fond of them is there a gauge of what size we should increase the pond to make life better for them ?

 

Hi Lazydays
The size doesn`t matter too much.
Having 10,000 gallons of water with a low oxygen content is much worse than a super oxygenated 1000 gallon pond

Commercial fishfarms overstock tanks by a huge amount, but compensate by using extreme filtering and direct oxygen injection, obviously overkill for a normal garden pond but the theory is sound.

If you over-estimate the oxygen, filter and flow requirements of the pond by a fair percentage, you`ll be hard pushed to kill the fish.

With a "normal sized" system, even a large algae bloom could reduce oxygen levels to dangerous levels.

 

The theory is good Hex, until you get a power cut on a hot night, then it all goes out the window and the strong survive.
Why live on the edge, or should that be, make the fish live on the edge.

 

Hi Pete
In that scenario the "adequately sized" system is also in a similar boat.
The average percentage of dissolved oxygen in the water will likely be lower than that of the over rated system at the start of the power cut.

The "adequately sized" system being almost "hand to mouth" (in some cases) will also be less able to cope with large swings in oxygen demand

 

Yes I take your point Hex,
Just wish I didn't have so many fish in my small pond, I'm reliant on electricity, thats no way to keep living things, or at least I dont think so.