Stressed Pygmy Corys?

[Dani0]

Hi all, new to the forum and fish keeping in general! I have set up a new 45 litre (12 ish gallons) heavily planted with a mix of slow and fast growers. I also have some houseplants stuck on the back to help deal with nutrients. The tank is hooked up to an oase filtosmart 100 and is fully cycled. I have a great little group of 9 Celestial Pearl Danios doing really well. The other day I thought I would spice things up and get 6 pygmy corydoras to help clean up the sand and I just love their little faces.

However, in the first few days that I have had them they quite regularly surf up and down the glass and zoom around the tank, particularly at the front in the corners. Then they go through short periods of acting as i would expect them to, sifting around foe food or resting. My water parameters are all good so no issues there. The Danios don't bother them at all. Is everything okay? Im worried that they are getting stressed by something but I don't know what. They also seem to stress the Danios out when they do this too. Any help would be greatly appreciated!

 

[gwand]

Both fish need soft to moderately soft water. What is the GH of your water?

 

[GaryE]

They aren't a typical member of the cory group, behaviour-wise. You're describing pretty normal stuff.

Fun fact (maybe). They gulp air through their mouths, at the surface. They extract oxygen via the intestines, and exhale through their butts. So surface gulping's normal, and when the bubbles appear - no worry.

 

[Innesfan]

As @GaryE stated, the three species of dwarf 'cories' behave differently from most others spending more time mid-water. That said, all cories tend to have a settle-down period when moved to a new tank and behave as if they are agitated for the first several days. Sometimes weeks. Do you happen to know which of the three dwarf species you have? One of them, Gastrodermus (formerly Coryodoras) hastatus spends much of the time mid-water and will school with certain tetras..

 

[Dani0]

I have moderately hard water but both fish groups have been bred locally and are used to the water chemistry so I don't believe that is an issue. But thanks foe the suggestion

 

[Dani0]

They aren't a typical member of the cory group, behaviour-wise. You're describing pretty normal stuff.

Fun fact (maybe). They gulp air through their mouths, at the surface. They extract oxygen via the intestines, and exhale through their butts. So surface gulping's normal, and when the bubbles appear - no worry.

Hi,

Okay that makes me feel a bit better thank you. And that explains the little breaches I see them do every now and then, I wondered what that was. I have no experience with Corys at all but already love them.

 

[Dani0]

As @GaryE stated, the three species of dwarf 'cories' behave differently from most others spending more time mid-water. That said, all cories tend to have a settle-down period when moved to a new tank and behave as if they are agitated for the first several days. Sometimes weeks. Do you happen to know which of the three dwarf species you have? One of them, Gastrodermus (formerly Coryodoras) hastatus spends much of the time mid-water and will school with certain tetras..

Hi and thank you for letting me know. I have never kept them before so am unsure of what is normal for them. I am pretty sure they are Gastrodermus pygmaeus. So it will be cool to see them schooling around! Hopefully they will find a nice balance in the tank.

 

[GaryE]

The important thing is to not crowd them, and keep the water clean. I would strongly suggest a partial water change every week, of around 30%.

 

[anewbie]

Little story on my group of 20 pymy cory. I had them in a 40B with some kribs and other fishes. When i first got the kribs i lost 2 and 2 other had tail damage but eventually the kribs learned they were harmless. Once this happened the pygmy would all pile up in front of the krib cave and when the kribs took their frys around the pygmy would follow them effectively using the kribs as body guards - knowing that the kribs would keep all larger fishes away. The most amusing thing was watching the pygmy intermix with the frys to graze and the kribs would leave them alone. Really quite amusing - who would have expected such long term behavior of mixing new with old.

Oh well - the dwarf cory are really interesting. Another thing you might notice esp in a larger aquarium is usually one will scout an area - declare it safe and then the others will come join it....