tiger barb swimming irregularly!

[gtorbe20]

Hi I am new to this forum and hoping someone could help me with a problem. I have introduced four tiger barbs to my 15 gal tank (ill move them to my 40 gal soon before they mature) which has two mollies, two glofish, a dwarf gourami, and a algae eater shark. Recently one of the barbs would float at the top of the tank vertical with his head pointed at the gravel. I have seen similar behavior when I lost a swordtail to what I believe to be a bladder problem. My ph and nitrate levels are normal. I did a 20% water change today and he seems to be swimming more normally but I was wondering if there is somethig I should be worrying about. Thanks in advance!

 

[alLexX]

this is OT,but what kind of shark?i dont think there are any sharks that can go in a 15 gallon tank.

 

[gtorbe20]

I forget what he's called. He's a dark grey with orange/ red fins but the store I got him from says they grow slow and not that big, besides if he does outgrow my 15 I can always move him to my 40. Any idea what the barb is doing? I read elsewhere on here that it may just be a camoflouging teqnique but that doesn't sound right. Its a pretty abnormal swimming pattern.

 

[alLexX]

no,sorry.