X-ray Tetra Has Developed A Dark Spot

[pleccytim]

Hi
One of my x-ray tetras has developed an odd dark spot inside at the bottom of its belly. I haven't added any new fish recently, I do 25% water changes every month, it shares the tank with 3 other tetras, 5 guppies and a pleccy. Any ideas what this is? Could it be internal injury or constipation or something? The picture isn't too clear, but I think you can get the general idea.
Picture at link following: [URL="http/bobmad386.blogspot.com/"]http/bobmad386.blogspot.com/[/URL]
Thanks

 

[WILDER]

Water stats would be good in ammonia, nitrite, nitrate, and ph.
Can you describe the spot in more detail as the pic not that good.
Any redness to the spot.

 

[pleccytim]

Water stats would be good in ammonia, nitrite, nitrate, and ph.
Can you describe the spot in more detail as the pic not that good.
Any redness to the spot.

I've only got those Tetratest strips that you dip into the water - they don't give an exact reading, but from what I can see the nitrate is way too high, nitrite normal, water hardness a bit on the high side, but nothing drastic, ph value 7.6 and carbonate hardness normal. I use StressCoat, Stresszyme, nutrafin cycle and EasyBalance fairly regularly, so not sure what to do about the nitrate. Could this be a cause of the spot on the fish? Incidentally, I'll go and invest in a proper test kit today so can give a more accurate reading later.

As for a further description of the spot itself, it's sort of reddish on one side. That same side has developed a white spot now. Looks like it could be fungus. Does that sound like a possibility?

Thanks

 

[WILDER]

Sounds bacterial with it being red and white.
You will need a bacterial med,
Good luck.