We moved in last year, and there was a pond (in the garden, complete with
liner, but no water. We filled it, (it's 3750 litres - is this medium or
large?) and left it for about 2 weeks then introduced plants.

We then added 15 goldfish and a pond pump. The fish seemed OK - we lost one
to ulcers over the last summer. Frogs, newts, snails and water boatmen all
took up residence, so we assumed we had created a good habitat.

However, from September to March, we lost 3 fish to ulcers. I did ulcer
treatments after we lost the first one, but it didn't seen to do much good,
so I did it again, then we lost 2 more.

In March, I salted the pond (1% dilution) and everything seemed OK for a
little while, so we got 10 more fish, making the total 21.

But since then, we have lost 6 fish in quick sucession. Some we can see had
ulcers, but 2 of them didn't have a mark on them. Today I can see that there
are 2 with ulcers that aren't going to survive for long, and one of those is
one of the new ones. I checked the new ones over before I put them in the
pond, and they had no signs of disease, so I can only assume it's the pond.

I feel awful, as I feel I'm just putting fish in there, and condemning them
to death. I have put a Medipad in yesterday, to see if that will help, but I
don't know what else to do. The pond is reasonably clear, and all the other
wildlife is surviving, indeed the snails and frogs bred this year.

Any advice would be gratefully appreciated. I thought goldfish were
reasonably low maintenance, compared to Koi, and that they were more
tolerant of fluctuations in condition. If they keep dying, I'm just going to
have to have a pond without fish, because I don't feel like putting any more
in there, just for them to die.

Sadly yours
Tracey