Odd cory behavior...they're all hovering mid-tank

[brendainnj]

I have a group of 6 cories that seem quite happy & normal except that for the last several days they have all decided they like to hang out in "mid-air".
It's almost like a school of glass catfish--they just hover there & wiggle. They don't seem stressed; they'll do this for awhile, then go about their normal poking around the bottom. But they are ALL doing it! It looks really weird, like they syncronize it or something. Sometimes 2" above the bottom, sometimes mid-tank. Is this normal?

Water parameters all fine, weekly 30% water changes. It's a 46g bowfront--kind of tall for their liking but other than that, they've seemed happy for the month I've had them.

 

[Old Scales]

If you keep your gravel clean and do your WC's to keep pollutants down then I'd say it is normal Cory schenadegans. I love those little guys just for there silliness. OS.

 

[BBradbury]

Your Corydoras

I have a group of 6 cories that seem quite happy & normal except that for the last several days they have all decided they like to hang out in "mid-air".
It's almost like a school of glass catfish--they just hover there & wiggle. They don't seem stressed; they'll do this for awhile, then go about their normal poking around the bottom. But they are ALL doing it! It looks really weird, like they syncronize it or something. Sometimes 2" above the bottom, sometimes mid-tank. Is this normal?

Water parameters all fine, weekly 30% water changes. It's a 46g bowfront--kind of tall for their liking but other than that, they've seemed happy for the month I've had them.

Hello bren...

If aquarium fish are acting differently, you can bet it's water related. Smaller water changes of less than 50 percent, do little to maintain pure water conditions, which is what most fish need to stay healthy. Corys need near pure water conditions.

I would start a more aggressive water change routine. Change half the water in the tank and do it every two weeks, faithfully. Diet is important. Corys are meat eaters, so I would feed a good variety of frozen foods. San Francisco Bay has some very good products. Freeze dried tubifex and shrimp are good. Hikari is a good brand. Flaked is also needed. Cobalt is likely the best for this kind of food. Algae is important too. Tetra has a good wafer.

Feed just a little of each every 2 to 3 days. These fish are foragers and need plenty of activity. Feeding a little less will keep the water cleaner and the large water changes will remove most of the dissolved wastes that are likely bothering the fish a bit.

Floating plants like Hornwort and Anacharis are good natural tank water filters. Just drop some individual stems into the tank. These are fast growing and will provide shade. Corys like an environment with subdued lighting and a well planted tank bottom too. Anubias is a good bottom plant that's low maintenance.

Just a couple of suggestions to think about.

B

 

[brendainnj]

Thanks, but I'm not understanding how a 50% WC every 2 weeks is better than 30% every week? AqAdvisor only recommends 16% every week--I thought I was being generous!

My water tests as follows every week: 0 Amm, 0 Nitrites, 10-20 nitrAtes. I have a planted tank, sand substrate, lots of hiding spots--driftwood, caves, plants etc. They show no other signs of stress. I feed a combination of New Life Spectrum sinking pellets, Omega One veggie rounds, freeze-dried blood worms. Have not tried the frozen yet.

 

[brendainnj]

update on corys...not good

Well, after my last post, I now have 3 cories left, and one is exhibiting same behavior as the others. I upped my wc to 50% each week, adding Prime as conditioner. The cories still "hover", then act normal foraging the bottom. Slowly, each individual becomes less active, retreats to another area of the tank, lays on its side, then eventually dies. The other fish in the tank are fine--1 dwarf guarami, 3 yoyo loaches.

Could my plants be leaving something toxic in the sand? I saw that on another forum.

My parameters are still Amm=0,Nitrites=0, nitrAte=10-20 ph=8.0 KH=161.1 GH=214.8 Temp=78

I thought cories were hardy. The tank was fully cycled when we got the fish.

 

[gemach7]

What type of corys? some might be intolerant of a ph that high. Also yolo loaches might be too aggressive to be kept with cory cats.

 

[brendainnj]

Sorry, they are loxozonous (sp?) cories. And the loaches have been absolutely fine w/them...before they started this odd behavior, the loaches would often school with them. I've seen no aggressive behavior at all, now they pretty much ignore the cories, even when one of them is lying still on its side.

 

[gemach7]

Try lowering the temp slightly, if im not mistaken those are from a pretty quick moving river in Columbia, i think their comfort zone is 70-75f. 1 degree a day so all can accustom themselves. 75 should meet all your fishes range.

 

[pip walters]

Well, after my last post, I now have 3 cories left, and one is exhibiting same behavior as the others. I upped my wc to 50% each week, adding Prime as conditioner. The cories still "hover", then act normal foraging the bottom. Slowly, each individual becomes less active, retreats to another area of the tank, lays on its side, then eventually dies. The other fish in the tank are fine--1 dwarf guarami, 3 yoyo loaches.

Could my plants be leaving something toxic in the sand? I saw that on another forum.

My parameters are still Amm=0,Nitrites=0, nitrAte=10-20 ph=8.0 KH=161.1 GH=214.8 Temp=78

I thought cories were hardy. The tank was fully cycled when we got the fish.

This sounds like some kind of osmoregulatory problem. These fish are almost certainly wild caught and will have come from amazonian waters of lower pH and hardness, so may be struggling to regulate the inflow/outflow of mineral salts, which may eventually lead to kidney failure.

 

[Bob Rowlands]

This sounds like some kind of osmoregulatory problem. These fish are almost certainly wild caught and will have come from amazonian waters of lower pH and hardness, so may be struggling to regulate the inflow/outflow of mineral salts, which may eventually lead to kidney failure.

I recently bought two new Cory nanus that did this. I have two others in a different tank that have been fine for months, but within a day the two new ones started hovering vertically mid-water and shaking from side to side. I tried a water change and cooling the water (it's a hot summer) - no effect. Eventually I isolated them in a large shallow Tupperware container. One died, the other recovered. A day later I put him in with the other two (different tank) and he has been fine since. No idea what the problem was, though it may have been tank-related. I'm not going to experiment to find out.

 

[Magaratz]

I was losing corys for no apparent health reason, but I had a yo-yo loach in the tank. It turned out it was a stress situation for them vs. the yo-yo. When the lights are out, you have no idea what may be going on. I turned in the yo-yo and haven’t had any problems since.