You're definitely not alone GT, most of us have been there at some point. The main thing is you're addressing it now.
You need to get your ammonia to 0 as this is toxic to the fish. I would do a large water change with temperature matched, dechlorinated water and then test again. Also test your tap water, just in case. What type of filter do you have? Sorry if you've already answered that. It sounds like you need to cycle your filter. There's lots of information on the nitrogen cycle around.
It would be great if you could get that pond built and keep your single tails in it. I had to rehome my shub last year as after a shaky start to life in a tiny tank he just grew and grew when I got a 4 foot tank. I miss him but it was the best thing for him.
What type of gravel are you using? We tend to recommend the 3-5 mm stuff such as quartz or dorset pea gravel. This is because the larger gravel can get stuck in the mouth whereas the 3-5mm gravel is too big to be ingested but generally too small to get stuck. If you're using the larger size, it might be worth considering changing it for the smaller stuff
Oh Frances, I'm so sorry to hear of your problems, poor Ziggi. Like others have said, you're a fantastic fishkeeper. We've all seen the lengths you go to to help your fish. Can anyone at GSGB recommend a vet?
Phew! I think I was looking for things to worry about. My hood should be enough concern, it's sort of balanced precariously at the minute. That's gonn ahave to be a job for tomorrow though, given how long it's just took me set up the darn filter.
That was not fun! And now my hood doesn't fit on. I couldn't fit the clips over the back of the tank as there is a glass sort of shelf thing in the way. I'm gonna have to cut some of the metal away on the hood so I can fit it on. I'd leave it off but the cat likes the look of the fish too much. I think I'd like a new tank sooner rather than later :)
Violet, your last comment about too large a filter has me worried. I bought the Fluval 305 which is for aquariums up to 300 litres, but my tank is only 160. Have I made a mistake?
External filter has just arrived so I will attempt to set that up. But first, I should probably go to work. Other half answered the door and carried it upstairs handed it to me and just said 'How big?! And you can get bigger? To filter what, a lake?' Hehe
Jay, I need to speak to dad and ask him if he fancies coming with me to ask for glass quotes, he's a plumber and is used to dealing with Doves (builders merchant) at least and probably a few other places too. He still doesn't seem too enthusiastic about the whole thing but I'm working on him. As soon as I get quotes I'll PM you
Just to add, the nitrate test is more likely to give a false low than a false high reading, suggesting it's the new one giving the duff result. If the reagent bottle that needs shook has been sitting on a shelf for a long time then it will need shook really hard, and possibly gently knocked off a hard surface to get the 'ingredients' back into solution as they will start to solidify when it is just sitting there. If you're using it regularly than shaking it for about 30 seconds will do but for a new bought test I would try shaking it for a lot longer, probably more like 2 or 3 minutes.
It also says that the numbers on an API kit are the date of manufacture and each one has a shelf life from that date. Don't know if they've changed that now? But it's all in that thread if you have a read of it.
You could also get some moss balls in there as they are good at reducing nitrate and, in my opinion, look very pretty in tanks too. Plus the goldies will enjoy eating them. Several of mine aren't 'balls' anymore
Do you know for certain it was flukes causing the problem? I know you had a lot of problems with flicking and scratching over the summer but couldn't actually see anything on the fish? Is there any way you could bring yourself to do a scrape to look under a microscope? The Johnson and Hess book has instructions on how to do one properly.
I can't answer about the Droncit I'm afraid but I'm sure someone can soon.