Tiny Bubbles On Top Water Of Tank

[Mercury2234]

Hey guys,

Have a tank about 30 gallon, with an Emperor filter 280; I am noticing lately that tiny bubbles are appearing at the top part of the water.

Can anybody shed light on what it means, or rather is it bad for the fish? Whenever, I do a water change, it all goes away, but next day its back on again...

Many thanks

 

[OldMan47]

Do you have any anabantids in the tank? Things like Bettas and gouramis build bubble nests, which are basically a raft of bubbles.