My fish are dying...
Discussion
We've got a naturally balanced pond, that is (possibly soon to be "was") stocked with fish (goldfish/ghost carp/normal carp/Orfes etc).
The ghost carp and goldfish have been swimming around merrily for the last 3 years, the Orfes and normal carp have been in there for around 15 months. All fish have been gifted to us, so unsure of age.
The morning after the hottest July day ever, there were 3 of the orfes floating. Initially we thought they had died of exhaustion as they seem to have been spawning and whizzing around the pond like nobody's business.
However, this morning, I found one of the larger carps on it's side with it's eyes clouded over. I'm not sure that the carp have been spawning.
We do have a fountain in the middle of the pond and turn it on when the weather is hot, just to aerate the water.
There are no marks on them.
Pond is around 10m long x 6m wide and around 1.5m deep (I think).
Lots of pond life. Lots of Iris's/Lily pads/oxgenating weed.
What's going off?
The ghost carp and goldfish have been swimming around merrily for the last 3 years, the Orfes and normal carp have been in there for around 15 months. All fish have been gifted to us, so unsure of age.
The morning after the hottest July day ever, there were 3 of the orfes floating. Initially we thought they had died of exhaustion as they seem to have been spawning and whizzing around the pond like nobody's business.
However, this morning, I found one of the larger carps on it's side with it's eyes clouded over. I'm not sure that the carp have been spawning.
We do have a fountain in the middle of the pond and turn it on when the weather is hot, just to aerate the water.
There are no marks on them.
Pond is around 10m long x 6m wide and around 1.5m deep (I think).
Lots of pond life. Lots of Iris's/Lily pads/oxgenating weed.
What's going off?
Warmer water holds less oxygen than colder water, so the hot weather will not be helping.
Do you have an algae problem? Algae photosynthesise during the day, but use large amounts of oxygen at night.
Are you running your fountain at night? That's the most important time when oxygen levels might be falling, because the plants stop photosynthesising and continue respiring - thus using oxygen. The fact that you've found dead fish in the morning lends weight to the suspicion that oxygen levels are getting critically low at night. Perhaps you could also get an air pump and a diffuser, and place the output at the bottom of your pond. This will drive water circulation from low down up to the surface and ensure the lower levels aren't becoming deprived of oxygen.
Also, it would be worth getting a water test kit to rule out any other water quality issues. I found this one gives a good rough indication of nitrite, nitrate, pH, hardness and chlorine, and is not horrifically expensive. Very easy to use. The only thing it doesn't do which would also be of interest is ammonia - perhaps get a separate kit to test that as well.
Test your water and tell us the results, and we can help work out what's wrong.
Edited to add: How do you top up your pond? Tap water or rain water? If you use tap water, consider using one of the test strips to find out what the chlorine level is, and also what the nitrate level is. Chlorine can be neutralised by various additives available from aquatic shops, and to a certain extent will be reduced by 'sprinkling' the water in rather than pouring it in. Your tap water could be surprisingly high in nitrates, which would contribute to any algae problem you might have. If you have a water butt collecting rain water, it's far better to use that for top-ups.
Edited again: Just realised how big your pond is. I guess a water butt-ful isn't going to top that up by much. So I guess you're using tap water out of necessity. And an air pump isn't going to,achieve much either! Maybe get a water pump, place it at the bottom and have its outlet nearer the surface, to create the water circulation I was talking about.
Do you have an algae problem? Algae photosynthesise during the day, but use large amounts of oxygen at night.
Are you running your fountain at night? That's the most important time when oxygen levels might be falling, because the plants stop photosynthesising and continue respiring - thus using oxygen. The fact that you've found dead fish in the morning lends weight to the suspicion that oxygen levels are getting critically low at night. Perhaps you could also get an air pump and a diffuser, and place the output at the bottom of your pond. This will drive water circulation from low down up to the surface and ensure the lower levels aren't becoming deprived of oxygen.
Also, it would be worth getting a water test kit to rule out any other water quality issues. I found this one gives a good rough indication of nitrite, nitrate, pH, hardness and chlorine, and is not horrifically expensive. Very easy to use. The only thing it doesn't do which would also be of interest is ammonia - perhaps get a separate kit to test that as well.
Test your water and tell us the results, and we can help work out what's wrong.
Edited to add: How do you top up your pond? Tap water or rain water? If you use tap water, consider using one of the test strips to find out what the chlorine level is, and also what the nitrate level is. Chlorine can be neutralised by various additives available from aquatic shops, and to a certain extent will be reduced by 'sprinkling' the water in rather than pouring it in. Your tap water could be surprisingly high in nitrates, which would contribute to any algae problem you might have. If you have a water butt collecting rain water, it's far better to use that for top-ups.
Edited again: Just realised how big your pond is. I guess a water butt-ful isn't going to top that up by much. So I guess you're using tap water out of necessity. And an air pump isn't going to,achieve much either! Maybe get a water pump, place it at the bottom and have its outlet nearer the surface, to create the water circulation I was talking about.
Edited by Dr Mike Oxgreen on Sunday 5th July 07:43
I lost all (literally, not died) my big Orfe, set up CCTV in time to see the last one go, and it was a fox, in the early hours, just dived right in with an enormous splash then dragged it off under the bushes, just a few scales left as evidence.
Been losing my goldfish erratically this year too, variety of sizes, no distress, fine one minute - lively eating, then dead the next morning - still looking perfectly healthy, but only 1 at a time.
I think the long cool spring meant they haven't come out of their winter slumber very well, and now the widely fluctuating temperatures is just too much.
Been losing my goldfish erratically this year too, variety of sizes, no distress, fine one minute - lively eating, then dead the next morning - still looking perfectly healthy, but only 1 at a time.
I think the long cool spring meant they haven't come out of their winter slumber very well, and now the widely fluctuating temperatures is just too much.
Thanks for the replies everyone, and apologies for my slow response!
Since my OP, no more fish have died, thankfully, although we haven't done anything different yet, besides keeping an eye on the fishes activity.
The pond works well in terms of staying at a decent level, so we only top it up when absolutely necessary, which isn't very often. After the first three Orfe had died, we were advised that due to the hot weather, the pond was giving off poisonous gases and to prevent that we should slowly sprinkle tap water into the pond and run the pump at the same time.
It does however sound like we had been putting the fountain/pump on at the wrong time. We had been turning it off in the evening and restarting it at around lunchtime the following day if the weather was hot. Makes sense about having it turned on at night now it's been pointed out!
On a side note, the pond is an established one - it's 40 years old. There has never been a filter or pump since we've been here and I guess many years before that too.
I don't believe my pond is overstocked, we have about:
5 x medium sized carp (say 450mm long)
1 x large Orfe (probably 600mm long)
4 x small Orfe/Goldfish (300mm long)
2-5 x wild ducks
A few common newts, frogs etc
The water is clear with no noticeable algae.
HOWEVER, there is lots of oxygen weed. Should I attempt to remove this? We usually do this early or late on in the year. I'm slightly reluctant to remove it atm, due to the fish eggs in there and disturbing the "silt", but obviously the living fish come first...
Since my OP, no more fish have died, thankfully, although we haven't done anything different yet, besides keeping an eye on the fishes activity.
The pond works well in terms of staying at a decent level, so we only top it up when absolutely necessary, which isn't very often. After the first three Orfe had died, we were advised that due to the hot weather, the pond was giving off poisonous gases and to prevent that we should slowly sprinkle tap water into the pond and run the pump at the same time.
It does however sound like we had been putting the fountain/pump on at the wrong time. We had been turning it off in the evening and restarting it at around lunchtime the following day if the weather was hot. Makes sense about having it turned on at night now it's been pointed out!
On a side note, the pond is an established one - it's 40 years old. There has never been a filter or pump since we've been here and I guess many years before that too.
I don't believe my pond is overstocked, we have about:
5 x medium sized carp (say 450mm long)
1 x large Orfe (probably 600mm long)
4 x small Orfe/Goldfish (300mm long)
2-5 x wild ducks
A few common newts, frogs etc
The water is clear with no noticeable algae.
HOWEVER, there is lots of oxygen weed. Should I attempt to remove this? We usually do this early or late on in the year. I'm slightly reluctant to remove it atm, due to the fish eggs in there and disturbing the "silt", but obviously the living fish come first...
Backseatdriver said:
Golden orfe need very high levels of oxygen. Keep the fountain and hopefully a filter running continuously.
They are a coloured morph of ide, Leuciscus idus . Ide are a fish of medium to large rivers and large lakes - they don't naturally occur in waters the size of garden ponds, unlike the ancestors of goldfish and (to a lesser extent) koi, so when conditions get marginal they're often the first fish to turn up their fins. Gassing Station | All Creatures Great & Small | Top of Page | What's New | My Stuff