with a new tank and no bacteria---max # of fish is zero. You will need at least 3" of small gravel in the bottom to begin the growth of bacteria and enzymes to neutrilize the ammonia, nitrate, and nitrites from the fish waste. Ammonia levels will spike quickly and become toxic with only a few small fish without the bateria. See a good pet shop and they can sell you a good "starter" bacteria, such as StressZyme. Regardless of your filter choice, it will need to have a BIO-Filtration component that operates continually.

I use the Fluidized Bed Sand Filter (model FB-900 by Pentair), it can handle overstocked fish or up to 900 gallons. Cost is right at $100. For waste I use Marineland Magnum 350 filters Ebay about $85).

Last edited by Rainman; 11/22/08 07:43 PM. Reason: lack of spelling