As stated by mike_sema, plecos will suck the slime coat off the bichirs.That slime coat is extremely important for fish. Adding the salt will help it build the coat up. Look in the poly threads, someone recently posted a picture of their ornate that had half of its slime coat sucked off by a pleco. Simple answer to keeping both plecos and bichirs.....buy another tank and separate them.
Glad to hear the nitrates are in order. Just keep up with the water changes.
To be safe, Id just go out and buy API aquarium salt. Its only 12 bucks for a big container that will last a long time. I believe the difference is that some table salts have iodine in them. And that is toxic for the fish. Not 100% sure on that but i think thats what i have read before.
Maybe a good picture of the whole body in the qt tank would help people find away to treat this guy.
