what is this?

[jetro]

I'm finding a film on my airstone can some one tell me what this is?

 

[gerald]

Fungus. There is some decaying organic matter in or on the airstone. Where was it prior to being put to use in this tank? (no, it wont make your fish sick).

 

[jetro]

The airstone was new but it has been in my tank for 2 weeks. I have another question the femal is turning to is side and the male seems to pay more attention to her does this mean they are trying to breed?

 

[gerald]

Strange that would happen with a NEW airstone, unless a spider or earwig or something crawled inside it and died. There's no fungus blobs or film elsewhere in the tank? Usually it grows on rotting food that didn't get eaten. Yes the female displaying her belly toward the male is usually a courtship sign. It doesn't necessarily mean they will breed soon, but its an encouraging sign.

 

[jetro]

I cleaned the airstone today when I did my water change. The rest of the tank looks fine but I will be watching it for further signs of the problem. As fr courtship they seem to be together a lot hiding in the caves. I have 4 panda corys and 5 cardonal tetra in the tank to could you sugest any other types of fish that might be suited for a 20 gallon aquarium?