Smells Like Mold. Algae?

The glass on top of my (48 gallon) tank gets green slime in one spot only (the same spot every time). It smells like mold. It keeps coming back after I clean it. So, I took the glass top off and am using a wire top instead (like for a reptile cage). The mold or algae or whatever it is doesn't grow on the wire, but it's now growing on the plastic crossbar on top of the tank. I don't notice it in the water or on the plants or fish at all. Just on the top of the crossbar. I'm wondering if it could be caused by the light? What kind of light would be best to prevent this? I have an Oscar and a couple of koi in the tank, along with a pleco. All are over 6 inches.

 

do you feed in the same spot where the remnants could be spashing up on the bottom of the glass and drying and causing the odor?

 

Welcome to FishLore!

I don't know that you can prevent it, algae kinda goes hand in hand with fish keeping

 

do you feed in the same spot where the remnants could be spashing up on the bottom of the glass and drying and causing the odor?

Actually, no. I feed from the side of the tank. The "stuff" is in the middle, on the plastic bar that goes across the top.

Welcome to FishLore!

I don't know that you can prevent it, algae kinda goes hand in hand with fish keeping

So, it's algae? Not mold? OK, I can deal with it better if I know what I'm dealing with. Thanks.

 

Is it kind of bluish? Sounds like cyanobacteria if so. It smells pretty foul and is slimy

 

Is it kind of bluish? Sounds like cyanobacteria if so. It smells pretty foul and is slimy

It's green.

 

Are you able to remove it with a scraper or sponge or by hand? Are you able to get a pic of it?