Hello - this is my 1st posting to the website. I have 2 zebra danios who have both developed what appears to be a bubble on their lower lip. I 1st thoguht it may be mouth fungus & so have treated them with Pimafix for 7 days. I think its helped a little but the bubble is still there. I have looked on the net & have found nothing that resembles what they have. I do a part water change each week & my weekly water tests show all is normal. Can anyone help?l 
