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Fin rot in L471 Pleco?


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Hi everyone! 

I was away this past weekend and when I got home I noticed my L471 pleco had developed some grey patches on it's sides that weren't there before the weekend. I decided to watch it for a couple days and today I noticed that his dorsal and tail fins appeared to have something that looks like fin rot. I'd really appreciate a second opinion on what this could be and maybe some advice on treating it. Sorry the pictures are not the best, my phone camera is not great. On the dorsal fin its an even grey line of rot but on the tail fin it's a little more ragged so I'm thinking its a combination of bacterial and fungal. 

In measuring the water parameters for this post I realized that nitrates are absolutely through the roof and the temperature is really low! I had no idea and I'm thinking this is definitely what's caused my pleco to get sick. 

I don't know why the temp suddenly dropped (it's supposed to be at 81 F, and it's at 77 F), I think the heater might be dying. Luckily I had a back up heater. I've also done a big water change immediately to lower the nitrates. But not sure what to do to help the pleco directly. 

Veery much appreciate your help! Thank you in advance. 

  • pH: 7.0 (test strips and liquid test)
  • Nitrates: 40 ppm - 80 ppm (test strips and liquid test) ** way too high**
  • Hardness: 160 ppm (test strip)
  • Nitrite: 0 ppm (test strip)
  • Ammonia: 0 ppm (test strips and liquid test)
  • KH/Buffer: 40 ppm (test strip)
  • Water Temperature: 77 F (supposed to be 81 F)

Side note (I tend to ramble so I'm putting all the unnecessary information in this side note):

I'm really surprised about the nitrates however since i was away this weekend I missed my normal weekly tank cleaning. This tank also houses my pea puffer who kills a lot of snails. Maybe the dead snails is causing nitrates to accumulate really fast. In future I think I will check for and remove dead snails daily. I'm also going to add a sponge filter to the tank, in addition to the existing hang-on-back. Will just have to really keep on top of my water changes. I feel bad that I let this happen. 



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Some of my juvenile Bristlenose get this it's when they get trapped and rub off their armour clad scales I increase water changes and add a small amount of aquarium salt 1 table spoon for 3 gallons and it usually goes back to normal after a week 

Edited by Colu
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  • 2 weeks later...

Thanks Colu and Fish Folk! Just an update: I did more frequent water changes and his colour is coming back. Also, Colu, I think you may be right about his scales getting rubbed off, because a lot of snails had gotten into the pleco caves and he was pretty wedged in there. He was frequently waving his tail trying to dislodge the snails, so I also cleared the snails out of the caves. Thanks for your help and sorry for the delay in my reply.


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