tank odor

Question
HI, I have a 40 gal tank.with 4 small oscars 2 small alge eaters,2 snails, I keep my tank clean but there is an ungodly odor coming from my tank,can you help me out thanks

Answer
Hi Steve
Try checking your water quality.  Make sure ammonia and nitrites are at 0 ppm, nitrates under 20 ppm.  I don't know how small those fish are-they won't stay small for long though :)  but, your tank is overstocked and that may be causing the odor(poor water quality).  
How often are you doing water changes?  For a normal stocked tank, I recommend weekly partial water changes/gravel vacuums of about 25%.  In your case, I would recommend doing two weekly partial water changes of 25%.

Try increasing the water changes, and you could add some carbon to your filter.  Carbon should also help remove the odor, but I would still recommend increasing the water changes as well.  

Good luck! And let me know if you have more questions.

Christy