Guppy Cant Swim Below The Surface

[doodlemonkey]

Hi- my female guppy all of a sudden cant swim below the surface without a lot of effort and a couple other guppies are picking on her. My water is all normal except for nitrate which is high, and i am replacing a little water every day to hopefully fix that. could this be why she cant swim right? all the other fish (there are 6 total w/ 4 guppies) seem fine, even though the 4 guppies are new to the tank. the tank is 6 gallons with filter, heat, and light. please help! thanks in advance

 

[WILDER]

What are your water stats in ammonia, nitrite, nitrate, and ph.
What do you feed the fish.
Does she look bloated.

Swim bladder is caused by bad water quality, injury, deformed swim bladder, infection of the swim bladder, poor diet, unstable temp, internal parsites.