Black dust in my tank?
Hi! I recently moved my betta fish (Celery) into a 2.5 gallon filtered tank. This was meant to be an upgrade from his 1 gallon / unfiltered tank. His favorite thing to do in his old tank was play in his fake plants, so in the new one, I decided to put a few real plants for him to explore. Things were looking really good for a few weeks, but I recently noticed this odd black dust that has settled on his little submarine and the leaves of his plants. There is also a slight film of sorts on the surface of the water. I don't really know what to do about this. I am worried that if I simply clean his tank the dust will come back. Is there something I'm doing wrong or is there something I should be doing that I'm not? Any advice is greatly appreciated.