Hello.
I have a shoal of lemon tetras ranging in ages from a few months to around three years. Last week I noticed a strange swelling on one of the older tetras , at first I thought this might be dropsy however the swelling only occurred on one side and there were none of the usual symptoms to accompany this. I telephoned my
LFS for some advice and they told me that it could possibly be a tumour and their was advice was to use a general tonic ? Since then the swelling has been steadily growing, I have taken a water test of my tank and the results are as follows.
P.H - 8.0
Ammonia - 0
ppm
Nitrite - 0
ppm
Nitrate - 5 -10
ppm
No other fish appear to be showing symptoms of disease or infection , I have included some pictures to help illustrate the problem

Any help on this would be most appreciated I also have a small quarantine tank if needed.
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