blue eyed lemon pleco fin issue

[Razberry910]

one of our Blued lemon plecos seems to have a fin issue. A while back we noticed a slight pink/red spot on the tip of its side fins. today I noticed there seems to be a fin issue. see attached pics.   any help appreciated 

20 gal. 75 degrees  other tank mates similar sized lemon pleco( I believe both girls), 5 juvenile green plecos, black shrimp

[Guppysnail]

I’m so sorry your pleco is having issues. Though I have never seen that in mine I have used Jungle fungus fizz tabs (nitrofurazone) and kanaplax (kanamycin) treated in the water not the food with 1 tablespoon of salt/10 gallons and added airstones with my long fin lemon blue eyes. That combination treat a very wide range of things gram positive/negative and fungal. My lemons never even seem to notice I’ve put all that in the tank. They just do their thing. Without the extra airstone/s and salt they do get a touch stressed so I recommend using both with that treatment. 

Im going to tag @Odd Duck in case there is a better approach. 
 

Use prime or the like to neutralize ammonia and nitrite during and after treatment as it does disrupt the cycle a bit  

Edited April 6 by Guppysnail

[Odd Duck]

Solid plan from @Guppysnail and I would recommend you pair it all up with making sure the water is pristine.  That looks likely to be fin rot with other fins a bit shorter than typical for longfin BN.  There might be other stressors coming into play so make sure there are enough hiding places and no squabbling over food, caves, mates, etc.