An ailment I cant figure out! (Ive searched)

Question
QUESTION: In my 55 gallon community tank (one bio-filter, two sponge filters, all three set high enough for water fall, and a four-inch air-stone), I've got a collection of various tropicals.  One 3-inch pink gourami, 2 4-inch plecos (will be removing one shortly to another tank, due to size), 2 yo-yo loaches, 4 varied chorys (lost one albino), 3 white and 2 black phantom tetras (lost one white and 2 black), a buenos aires (lost two), a couple of rasbora (lost a couple), a couple of small black/yellow spot tetra-type fish I have yet to identify (they seem to get no bigger than an inch), and a honey gourami (lost one other).  This is an established tank of over three years, which consistently has a ph of 7.0 (never acidic or base), and zero nitrite.  Ammonia has never appeared to be an issue.  Water is added (1 - 2 gallons) ever other week, but with water conditions always optimal, I've never seen the need to do water changes.  My question concerns the honey gourami, but pertains to several other fish I've lost.  Almost overnight, a fish will exhibit a "bent-back", with an obvious difficulty swimming; generally, the injured fish appears a little darker, with a great deal of gasping (only the ailing fish shows these symptoms, no other fish will).  The fish will occasionally swim to the surface, but most of it's time is spent gasping at the bottom of the tank.  Can you help?

ANSWER: Hello!

It is tuberculosis. Caused by poor water quality and mal nutrition.

You say your ammonia and nitrites are good but that doesn't matter....at all. Even the very dirtiest tanks have 0 ammonia and nitrites, all tanks over a month old do. What matters is the nitrates. That's nitrates with an "A".

Your nitrates are the main thing you want to moniter. Nothing else really matters in a tank over a month old, and ammonia and nitrite certainly have nothing to do with the water quality of established tank.

Nitrates should never go over 40 ppm, but it is best to keep them under 10ppm. I'm going to take a random guess and say yours are well over 100ppm.

Get a nitrate test kit and tell me the results.

Now, on treating. You can not treat tuberculosis, you can only prevent it. Once the spine is deformed there is no hope for the fish. I would advise either giving it a quarentine tank to die peacefull in, or euthinze it with boiling water.

WARNING! Tuberculosis can and has been known to pass from fish to humans. Be VERY cautious when working with your fish, and never touch them with your hands when they have this disease.

-Nick

---------- FOLLOW-UP ----------

QUESTION: I will do so immediately (admittedly, I am an amateur, only been doing this as long as I've had my tanks, about three years).  As most info on fish seems so generalized, and haphazard, could you go ahead and tell me what I will need to do (I'm betting your analysis is spot-on), to remedy the situation, once I've confirmed it?

Answer
Water changes, water changes, and more water changes. Your water change schedule is the single most important thing you will ever do with your tank.

Ammonia is caused by fish waste, over time, your tank develops beneficial bacteria that turn this ammonia into the less toxic nitrite. And again, into the less toxic nitrate. Although, nitrate is still very toxic in large amounts.

Luckily, nitrates are very easy to remove.
There are two things that can efficiently get rid of nitrates. Live plants, and water changes. The latter being the best, but plants can help very much too.

You must do 50% water change once a week, or preferably, 25% water changes twice a week.  However, for the next two weeks I suggest you do a 25% water changes every other day to get your nitrates immediatly down to a safe level.

Also, you could pick up some very easy to care for plants. Java moss and java fern require no special lighting, and no fertilizers, but can still take your nitrates down a bit. No substitute for water changes however.

-Nick