Oily Film On Water Surface

[Meeresstille]

I just used some paper towels to blot up this oily film in my 5 gallon female Betta tank. It has an Aquaclear 20 filter running on it, but because the flow seemed a little strong I've added a sponge at the bottom of the filter out-put. The water would normally there just splash back into the tank, and now it falls onto the sponge which slows the current in the tank.
 
I'm now wondering if the reduction in flow is the cause for the surface film or if there is something else going on? This tank was normally used as a QT. I've set this tank up as a 5 gallon Betta tank last week (the filter has only mature media and is cycled). There is only this one female Betta in there and maybe 3 or 4 shrimp that have found refuge in the filter compartment.
 
Also, this little Betta has been snacking on a few shrimp that I've added as tank mates. Could her eating the shrimp have caused the oily film?
 
Edited to add: The Betta seems fine!

 

[attibones]

The oily film is quite normal. Most betta fish will produce it. I'm not sure what it does or if it is even harmful, but it is normal. I've only seen it in my tanks, though, if I didn't have enough surface agitation to clear it up. 

 

[Meeresstille]

The oily film is quite normal. Most betta fish will produce it. I'm not sure what it does or if it is even harmful, but it is normal. I've only seen it in my tanks, though, if I didn't have enough surface agitation to clear it up. 

Thanks attibones! 

I will see if I can tweak that outflow so it's not too strong and not too weak! Hopefully that will fix the film issue! 

 

[Wildbetta]

Yeah a surface film is normal.  Most people do not see it because the surface agitation gets rid of it.  It shouldn't really harm anything and only really looks bad.

 

[Meeresstille]

Yeah a surface film is normal.  Most people do not see it because the surface agitation gets rid of it.  It shouldn't really harm anything and only really looks bad.

Phew, thanks for easing my worry! 

 

[Mamashack]

Have you recently added a magnetic algae cleaner? I bought a new one for my platy tank and within minutes of adding it to the tank there was an oily film on the surface of the water. Like you I tried to blot it with kitchen paper roll but the only thing that shifted it as others have said was surface agitation. It still occurs to a lesser degree whenever I use the algae cleaner so I think in my case it's something to do with that. Just a thought and not harmful anyway as far as I know.

 

[wrightt3]

If you have a small jug or something, try scooping some of it up. I find it works pretty well but as mentioned above it's not harmful at all and is present in most tanks and even nature (just doesn't look very nice)

 

[Meeresstille]

No, Mamashack, I don't have a magnetic algae cleaner, it must be from the slowed surface agitation. My other two tanks have more surface agitation so I haven't seen it there. I wonder if your magnetic cleaner may have been treated with some kind of oil for storage?!
 
The jug is a great idea, wrightt3, I remember using a jug on the 30 gallon before I upgraded it to a 40 gallon (I am now running two filters on the big tank). When I saw this film on my newly set up 5 gallon I kind of panicked and got worried for the little Betta-girl's health.