[guppyart]

I have algae like that in 30 gallon tank and there is only 3 guppies in it as to the ammonia it might be that your water has a high ammonia content but another thing that might be causing that is syphon the gravel incase you have excess food or poop that can have quite the effect on the waterin the tank and the gourami don't worry they do that alot cause they can breath air but when the other fish start doing that you might have ammonia at to high a level hope this helps you I have had that problem myself and there is not much that you can do alot of the time other than just sit it out