Do Giant Danios Croak/grunt/etc.?

[GoldfishAttentionSpan]

There is a strange noise coming from my 10 gallon quarantine tank. It has 5 giant danios, and 1 male guppy (in a breeder net).

Maybe its one of the air pumps or something, but could it be the fish?




ETA: Ummm... turns out I just have a hole in the air line that burps a bubble now and then. Nevermind. XD