Is there a faster way to kill little black ants?
Most likely there is no way without any poison. The best way I could think of would probably be to get the little ant traps with poison inside and set it down by the fish tank. The ants bring the poisonous food back to the rest of the ants in the colony and they all die. You can pick up a 4 pack at any Walmart/Target/similar store for a few bucks, you might even be able to find one at a dollar store. If your worried about it being poisonous because you have a pet, just put it behind a dresser or something where it can’t be easily reached.
I’ve never dealt with this before, but I would start as the source. If there is a place they are coming into your room then you should close that off. It is more often than not that the colony is located outside your house. Another thing you could try also would be to put some food outside your house in a hope that the ants would return outdoors, kinda doubt this idea but it’s still an idea. The best way that I read to get rid of them is to use ant bait. Apparently it doesn’t kill the ants immediately so that they can take the bait back to the rest of the colony. Your house is one big restaurant! Good luck.