Loach deaths...insight, please?

[laloach]

Hello all,
As I have frequented this website as an invaluable tool in the last 3 years, (the time that I have had clown loaches) this is my first posting.
May I preface this by saying that while the topic may be a bit redundant, I have been fortunate not to have had any serious issues until recently. Now that this issue has impacted me personally, I hope that I might have some insight and assistance from you, the experienced. Thank you in advance.
I have a 75 (US) gallon tank, filtered by a Fluval 405, and an AC110. My pH is about 6-7 (varies when I do a water change, but becomes acidic as the tannins are released from the Malaysian driftwood in the tank) the nitrates are around 5,and nitrites are at 0. I keep the tank at about 79 degrees F. Water changes of about 40% with a python every 5 days. Oh, and I have a 1/2" of pool sand substrate, and feed a mixture of flakes, shrimp pellets, fresh organic veggies, and algae wafers.
Until last week, it was stocked with 3 botia kubotais, 5 clown loaches, and 6 rams.
About 6 months ago, I realized that the smallest clown (about 3"), in spite of a healthy appetite, was bony, so I treated the tank with the recommended levamisole hydrochloride treatment using the yellow pill form, (the rams were not in there at the time) and things seemed to be better. I got the rams about a month ago, and 2 weeks ago, added them to the tank after qt'ing for about 2 weeks. The smallest clown became skinny quickly, I retreated the levamisole, to no avail. While the other loaches appeared better and to have had a growth spurt, the smallest one didn't make it. Then the largest one, Gorda(about 8"), became vibrant in her colors, but suddenly became extremely lethargic. Within just a couple of days, I lost her too. The next largest clown (about 7") followed almost immediately after I did a major water change, took the driftwood out and scrubbed it, and put an organic lemon slice in there as a snack.
What I noticed when taking out the deceased clowns was that there appeared to be red, almost puncture looking marks on their necks and on Gorda, the largest, a little around her mouth. Also, previous to the demise (about a day or two), the affected loaches would appear to have labored breathing,and sleep on their sides for long periods without eating. The loaches have always got along famously, and I had not ever see them quarrel, so fighting seems to be out of the question.
I am at a loss as to what to do next. I know 2 loaches are not happy just as the pair, but honestly, at this point, I am constantly waiting to find them dead as well. Could this be tuberculosis?
Upon realizing how lengthy this is, I certainly hope I have supplied all of the information needed to assist. Thank you again.

[Ded1]

Could this be tuberculosis?

Cant help you a lot, very sorry.
But I must say that I doubt that it is TBC. It cant just appear in tank from nowhere, just like that. You have to put a fish with TBC, to contaminate the other fishes, but you didnt put any new organism in tank, so i doubt it it is a TBC. And certainly can not have incubation period of 3 years.

[Diana]

Even adding the Rams after such a short quarantine period, I would not expect to lose the Loaches to TB that fast. My understanding is that TB develops more slowly than that.
Could the Rams have brought in some other parasite or disease? Did you treat the Rams with any sort of preventative while they were in QT?

I do not know what might have caused the red spots.

Could the temperature have gone up, perhaps while you were at work, and stressed the Loaches?

[Total Package]

Could you have a case of ammonia poisoning? It is quite possible that the filter became overloaded with the introduction of the new rams.

Typical symptons include lethargy, loss of appetite, redding of gills, red streaks (spots?)

[laloach]

Thank you...I appreciate the responses.
I am at home currently and keep an eye on my tank throughout the day (whenever I can )
I didn't medicate the rams, because the colors were so vibrant, they are plucky little buggers, hence the shortened qt - they really did look great.
However, I have just lost another loach, this one had obvious swelling on its underside, with a purplish cast to it, but no lethargy, just difficulty swimming due to the swelling. Lost a ram yesterday as well.
I did another major water change and am waiting to see what happens next. Am pretty discouraged about the dissolvement as opposed to evolvement of my tank. Good water changes, food, TLC.... WTF.