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My marble sailfin (sorry, new to the L numbering system, don't know which is the right one) had adopted a new behaviour in the last week. Every 5 minutes or so (day/night, doesn't seem to matter) he will go up to the surface, release a couple of large air bubbles through his gills, and then take a swallow of air and go back down.
As well, I have found waste containing small air bubbles floating at the top of the tank.

I'm puzzled by this apparent imitation of anabantoid behaviour...he appears perfectly healthy, other than slightly accelerated breathing rate - no signs of disease that I recognize. He eats well, his tank roaming patterns have not changed, and he doesn't appear to be in any discomfort. He did manage to split his tail about two weeks ago while thrashing his tail at the surface during a violent storm. (only fish in the tank that reacted to it)

The pl*co in question (Bob) is approx 1.5 years old, 12" long. The tank is a 70 gal, Fluval 404 filter running wool/carbon/biomedia. Tank conditions are quite stable, 0ppm NH* and NO*, Ph 6.8-7.0. Temp has been stable at 78 for a couple of years.

Does anyone have any idea what's up with Bob? Any info would be greatly appreciated, I'm starting to get worried about my favourite finny denizen.

That's normal behavior in some loricariids. Some are known to use their gut as an accessory breathing organ to obtain oxygen directly from the air.

Heok Hee

As Heok Hee pointed out, many loricariids are capable of taking atmospheric air. Most interestingly, the other night I watched a recently acquired Chaetostoma do this. I have never seen this behavior in Chaetostoma before, but maybe all members of the family (or atleast Ancistrinae/Hypostominae) can do it.

*agrees with HH* Nothing to worry about. My pellegrini pleco does it too, not so frequently though. Only strange thing about it is that you have never observed this behavior before. Oxygen level in your tank might have dropped, have you changed anything? I don't know the reason why he does it now if he never did it before but it's not a disease or anything like that. Bob is fine

PS: If you want to know his L number post a picture of him in the "What is my catfish" forum, maybe someone can ID him.

Wow, I never expected to get answers that quickly. Thanks to everyone, I'm glad to be able to relax about Bob.

As for the question about oxygen levels, no, nothing has changed in the tank, and nobody else seems to be breathing any different. I have adjusted my filters outflow to disturb the surface even more though, I'll let you know if the behaviour changes at all.

Thanks again!

I think it something all Loricariids do. I have seen it in Otocinclus and Lamontichthys oddly enough although it tends only to happen if the temp. is high and the filters aren't running as well as they should.

Anyone seen Pimelodids do it? I could swear my Pimelodus do it but I've never caught them at it, just forays to the surface maybe looking for food.

Jools

Jools,

I recall reading somewhere that some pimelodids do just that (utilize atmospheric oxygen). The problem is I've forgotten where I read this, and whether or not I have the paper. Don't really feel like digging through hundreds of papers in my reprint library at the moment.

Heok Hee

Well thanks SmilingSyno, you appear to have been right on the mark about oxygen levels.It's been 24 hours since adjusting my filter outflow to disturb the surface more, and Bob seems to be going up less frequently than previous.
Could be coincidence, but I'm wondering if the long power outage during the storm de-oxygenated the tank more than I realized. I did do a water change after to get some more in there, but maybe it wasn't enough...

I agree with Jool. Heard from a friend that plecos gulping air from the surface when the temp in the tank is too high!