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Hi, one of my bristlenose plecs had a small cut on its face and now it’s got a lot worse. It’s dorsal fin is slightly red and it’s body is starting to show red patches.I’m not sure what’s happened or what it is . The Ammonia is 0 nitrite is 0 and nitrate is around 40ppm any advice would be appreciated

Hi FishKeeper,

Normally I'd say that looks like bacterial infection caused by bad water quality. However, the ammonia, nitrite and nitrate levels you mention are great. Of course, there can be other issues, such as pH that can distress fish. What is the pH? When was the last water change?

I've tried a lot of medications over the years, and I've had relatively poor success treating with medications. My first impulse would be to do a huge water change (70%, if you think the tank can handle it) and add an extra airstone to boost aeration. That said, if your water is very hard and if your pH is rather extreme, and big water change causing a significant pH change could be worse. In that case, I'd do several smaller water changes (20%-30%) daily for 2-3 days, then follow with a big 70% water change.

Good luck.
Eric

Hi Eric, I live in Scotland so I have really soft water with very little KH so the ph can fluctuate a lot more. The last water change was done yesterday but before that was about a week ago. The ph is around 7.

FishKeeper wrote: 15 Feb 2023, 22:27Hi Eric, I live in Scotland so I have really soft water with very little KH so the ph can fluctuate a lot more. The last water change was done yesterday but before that was about a week ago. The ph is around 7.

Thanks for the info. A very soft water is great. When the water is so soft, I don't worry much about the pH. My tanks routinely swing down to pH 4 without bothering the fish noticeably (and some breed at that level).

With that info, then, I'm at a loss, other than to suggest go for the big water change, just to be on the safe side. I do suspect bacterial issues, so if you are comfortable with antibiotics, then give them a try. Sadly, I don't know which to recommend.

Good luck,
Eric

Thanks Eric will give it a shot cheers