Swordtail swimming weirdly?

[Fishingforfish]

I've noticed that my swordtailS have been swimming in an odd manner lately. There are only 2 of them, and they both do the same thing so I don't know if it's normal or not. The tank is currently bare bottomed, and what they do is swim with their mouth pointed to the bottom of the tank, so their body is slanted, then speedily swim across the other side of the tank. Is this normal? Lol

 

[Fishingforfish]

Not the best picture, but I've managed to get a picture of what it looks like. Actually, they're bodies are a bit more slanted than this..

 

[henningc]

No it is not normal unless there is a light source under the tank. Can they swin normally?

 

[Fishingforfish]

Yup, other than that they swim fine. I've noticed that they're really fast swimmers, it's hard to take a normal picture of them without them already on the other side.
Oh, and it's bright because I turned on the lights just to take a picture, it's hard to see when the light is off.