I have absolutely no idea about pond keeping. However, my grandad has gone travelling for 7 weeks and has left his neighbours to feed his fish.
Yesterday we got a call from his neighbour saying that he found two fish dead and floating on top of the water on Saturday. We went round and pulled another 5 out. None of the dead fish seemed to have any noticable problems apart from that they were really bloated.
The others seemed to be gulping for air at the surface and some were even just hanging near the filter output. My dad pulled out loads of weeds (as my grandad hadn't even bothered to clear the pond before he left) and he put the fountain on which seemed to make the fish look a lot happier.
Thanks for your help. Like I said, i've never had a pond and don't know anything about it, but have read some of the posts on this site in the pond section, and basically it sounds like the same sort of rules to follow as all other fish. I had a look round my grandad's house and garden and couldn't seem to find any testing kits or anything like that.
As i said, after my dad had pulled a lot of the weed out and started the fountain they all seemed to perk up a bit. We have asked the neighbours to put the fountain on every day from now on as it defintely looks like it increases the oxygen.
Apart from the filter, I really couldn't even tell you what my grandad has got running.
It also seems like he has got an awful lot of fish for the size of pond (don't ask me how many or the dimensions of the pond because I am hopeless with estimates!) Some of the fish are absolutely enormous too. There was a HUGE black and white fish (sorry but I don't know breeds!) who was the one that was gulping near the filter. I hate seeing a fish that size struggling.
Either way, they do seem better now that the weed has been pulled out and the fountain is on.
As Inder says, it does sound like lack of oxygen. Has the filter been cleaned I did see mention of that? Did your granddad leave feeding instructions with the neighbour and are they being followed? I am wondering if the neighbour is putting to much food in and some is not being eaten and rotting. Do you know if your granddad has any water test kits? Something is, for some reason, saying to me check the water for nitrites and ammonia. Fish problems aren't really my thing so I would suggest a browse of fishdoc or koivet if problems reoccur.
There is a filter, but i don't know if it has been cleaned, and really wouldn't know how to do this.
I couldn't see any testing kits. I have some but they are for a tank, not a pond (don't know if it makes a difference?)
The neighbour can't be overfeeding and my grandad has got a measuring pot type of device! It looks like a small cup on a stick (sorry my descriptions are rubbish) and they just fill that up and that's how much the fish have.
I initially thought that it must be something to do with the water. I'm not sure now though. It's been 2 days since we pulled the dead fish out along with a load of weed and put the fountain on, and no others have died. It might have been the oxygen? I'll keep updating.
Just thought that i would update this post. Grandad is back today. No more fish have died since we pulled those others out so i think it must have been that there was no enough oxygen in the water and since the fountain has been on everything has been ok.