Black Moor Goldfish poorly fish

Question
Hi Nori,

I have just eliminated major lice infestation on my Black moor fish, using a mixture of anti white spot and anti crustation parasite solutions.  But it still looks very ill and has since lost most of its rear tail.  So have treated water with disease safe, not sure what to do now?

Also I have a nitrate test kit, but am unable to get the level down to zero, even with a fresh water change?

Have also been doing regular water changes since I've had it, four weeks ago.  

Your advice on this matter would really be appreciated as our two other fishes have previously died.  

Answer
Hi Paul,
Thank you for your letter. Sounds like you have discovered the dark side of the hobby. I encourage you to consider following my holistic tank care plan. It might save your fish, but if worse comes to worse, I encourage you to try again using my holistic system.
Print this out:
http://steamboats.com/aquarium.html
My system is based on prevention and detoxification. Prevention is to prevent water pollution by limiting food to only a couple flakes per fish per day. Then detoxification involves friendly bacteria that conditions the water to make it more like a natural eco system.
Please stop all feeding, stop all chemical treatments, and buy a bottle of "Cycle" and follow the instructions on the label. Keep it in the refrigerator between use. You may also follow the emergency care instructions at the bottom of the page.
Write back if you want to discuss further. I am here to help.
Nori