detect sickness

Question
QUESTION: I would like to know -  when you buy a new fish and put in the tank, how long does it take for the fish to show if it is sick or not?
I have experienced buying fish and putting in my main tank right away, and later learned they came with fungus and killed most of my healthy fish (that I had for a while), so now I have a second tank ( a hospital tank . I put the new fish in, right when I buy, to make sure they are healthy before I put them on my main tank. So, I would like to know, how long do I need to keep them in the hospital tank until a I am "SURE" they don't have "ANY" diseases.
Thanks a lot!!!

ANSWER: Hi Andrea
Very very good idea what you're doing.  I would suggest at least 2 weeks as a minimum.  I know some people say at least 4 weeks minimum.  Even then, it's no guarantee but that does help.  Some infections like ich tend to show up when the fish is stressed, so just moving him around may be enough to lower it's immune system and allow the infection to start up.  
Some people will automatically medicate the fish with antibiotics and antiparasite meds as well.  That's what I've started doing too for the few fish I've recently bought, since the stores around me are really kind of pathetic regarding their fish.  

Christy

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

QUESTION: I recently purchased 3 angel fish, all appearing to be very healthy and active. I placed them in a separate tank (as I always do for new fish) for the past 10 days, to make sure they would not introduce anything into my main tank and insure their well being.

A couple days ago, one of the angels stopped eating and starting staying towards the bottom. Yesterday - it died.

Now, I have a second one that is not eating and staying near the bottom - still appears healthy. The third is active, eating, and appears very healthy in all regards.

Any advice on what may be occuring and what I might be able to do ?



ANSWER: Hi Andrea
I would first make sure the water quality is good-ammonia and nitrites at 0 ppm, nitrates under 20 ppm.  Then, you said they appeared to look healthy and fine, so I would suggest a medicated food-both antiparasitic and antibacterial to cover both possibilities.  I would feed them that for at least 5 days.

Good luck!

Christy

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

QUESTION: I changed my tank, I got 6 medium-size silver dollars, 1 geo  and 4 pleco suckers for 150 galons tank. Is 4 suckers a good number or too many for my tank?
Should I feed them at all? At present,I have visible algae, but if/when I do not see algae...will it mean I don't have algae? Or, will I still have "unseen" algae and they will still can be sufficiently fed?   
Thanks again!

Answer
I suppose it depends on what kind of plecos you got.  That is a large tank, but one pleco is usually very sufficient at cleaning a tank.  You definitely will need to supplement their diet with vegetables and other foods.  I would start doing it right away.