[StirCrazy]

Originally Posted by Caine

Sounds like black beard Algae.

Except bbeard algae wont hurt any fish. So that wouldent cause the original problem.

I have a couple questions though.
When you said amonia nitrate ect all normal. What are the actual values of your amonia, nitrate and nitrite. Also what is the ph of the tank and the hardness of the water.

It is a good idea to get better food but that isnt causing this.

I agree you need to do larger waterchanges, if your doing them weekly at least 50%, i used to do monthly ones of 90% on my planted tank.

Also your slate shouldn't cause a problem, but you can check it by putting a bit of vinager on it, if it does nothing it is safe to use. If it fizzes up dont use it. Also
You said you have sand in the bottom, what kind of sand?

One thing that struck me funny is it seems like your trying to conbine two opposit enviroments in your tank. The plants you have are a lower ph, soft water enviorment, but the fish you have listed that have died are all higher ph very hard water enviorments, when you start adding plants the will lower the ph of the water on there own and 10% water changes quite possably wont be enough to keep it up.

Oh also what are you using for a water conditioner?

Steve