fish breathing at surface

Hi, I recently got some guppies for my first fish tank and they spend most of their time at the surface. Is this normal? I have a filter installed and an airstone installed. The airstone seemed too powerful so I keep it on for a minute at some times during the day so I don't stress out the fish.

I have 6 fish in my tank, 3 guppies and 2 balloon mollies. However, since last night, I’ve noticed they’re all swimming around at the surface of the tank. Particularly the guppies. I’ve got no clue why because I have a pump that sprays bubbles so I’m sure there is enough oxygen in there for...

Ok - background. 72 gallon bow. low tech planted (no C02/ferts/anything), predrilled with overflow/filter housing. Filtered by two Fluval 405s with outtakes housed inside the filterhousing to reduce flow for discus. One filter is 3+ years old and the other is under a year old. I had been...