Do you happen to be using aquarium salt in the tank? A lot of larger retail pet places recommend adding a low dose diluted amount to freshwater tanks for tropical warm water fish, so lots of people do. The rub with that is not all Tropical warm water fish can handle salt. Unfortunately just because they sell fish doesn't necessarly mean they know enough about caring for the many individual species. (You can usually see that in how they have agressive fish dumped right in with the passive fish.) Now that I have strayed from the original subject here is the point of my salt question... Salt will kill a pleco. It burns their gills and dehydrates them. If a pleco is put in a true salt water tank it will die within hours. And even in lower amounts it is deadly to them, it just takes longer.

I haven't used any salt in the tank. What else could it be?

If the second dead pleco came from the same store, it may well have come from the same stock, so you may have gotten fish that were sick before you got ever put them into your tank.

You didn't say how large they were, but BN's can be touchy, especially when very young.

I know this was posted over a year ago, so this might be a dead topic, but I'm having exactly the same problem, so if you've gotten any answers I'd love to hear them. PLEASE!

Plecos can be prone to white spot and because of their thick skin it normally attacks the gills. Not a spot on the fish that you can see but the fish is heavily infested just the same.

I have one pleco that I wish WOULD just up and die. He bullies the other fish. But NO, he's healthy as anything, the little turkey. OH WELL>

Could it be the food? Or lack of it?

try this, and they will eat at night.

Get some iceberg head lettuce. The stuff that comes in the round. Take only the greenest outside layers  IMPORTANT IMPORTANT IMPROTANT  and boil it.

Use LOTS of water in the pan.

Boil it twice. It will stink.

Boil it once. Drain the water off. Then put it back in the pot with fresh water and boil it again. If peeps in the house tell you something smells terrible  like boiled lettuce  you are on the right track.

After its thoroughly boiled. Rinse it off. Before bed, shred a few pieces into the aquarium. This should allow your pleco to find it over night.

this can be done once a week and is an amazing thing. They grow very fast.

hope it works

dKB

Ya fouls my pleco dead too. It was fine before and I just found it dead today covered in white film. No clue what happened.