Shy Corydoras Habrosus

[frothhelmet]

I have 11 dwarf cory habrosus in a 60l tank on sand. I initially got 8 of them in 2016, but they regularly breed for me and some young survive naturally. They used to be real brave, out and about wriggling all the time, but in the last year they have gotten shier and shier. Six weeks ago I had to move them to a different tank and as a consequence they have become crazy afraid of me - like if I enter the room 10 feet away they explode towards their hiding places. I never get to see them unless I go ninja mode. It's weird because there is an endler and 21 ember tetras in the tank as well that are all over the place as dither fish, and yet the cories are still pusillanimous pansies. Any advice to return them to their former brave selves? My only thoughts are buy 6 more, or try to raise some more young, or buy a dither bottom fish like a Brochis - (no idea if they are good dither fish). Any thoughs about what might work?

 

[ScareCrow]

Have you reduced the number of places or the distance between places to hide? I find that some fish will only want to go so far from cover and are very skittish if on the outer limit.
Has the light intensity increased?
Have you changed to a lighter colour substrate? I don't know about habrosus but some species prefer to be on a darker substrate.

 

[frothhelmet]

Here is the 35l tank before the relocation

And here is the 60l tank after. One change that I do notice, now that you mention is, is most of the floating plant surface cover has died off (because I started growing some plants out the back of the tank, and the competition for nutrients kills my dwarf water lettuce). Perhaps this was a key to their former non-skittishness? All the other factors you mention now seem much improved.

 

[ScareCrow]

Sorry I meant if you increase the distance between hiding places or reduce the number of hiding places it will possibly result in them being more nervous. It looks like the distance between hiding places has increased as the footprint of the new tank is larger.
As you say the surface cover has reduced, which may also be a factor.
I should say I've not kept corydoras so this is all speculation based on observations of other species. Hopefully someone with more Cory knowledge will be able to provide some insight.

 

[alto]

C. habrosus is a shyer cory, if you want to add more, I’d begin with more Habrosus (dwarf cories seem to consider the 20’s a decent shoal ), you might also add some Pygmy Corydoras if you feel like you want some other fish “texture”

The most brave I’ve observed C habrosus was in a heavily planted shop tank where (people) traffic was common - I think that fish become accustomed to level of vibration and movement outside the tank and react accordingly

Was the previous smaller tank in an area where you were more present?

I’d also add more plants/cover - surface plants are cheap(est), perhaps epiphytes attached to stones placed on the sand, some driftwood that creates shadows and hollows (at sand level) etc and see how this improves fish behaviour

I would not add any of the larger Corydoras (esp Brochis which can be quite overwhelming/dominating) - especially as the tank footprint seems smaller than expected for a 60l - looks more cube shaped in photo?
Pygmy cories are less bottom oriented, Panda cories are one of the smaller species and seem less dominant BUT they also prefer cooler water so check temperature compatibility for new/current fish

 

[Driftless]

I have a number of Cories in my tanks including yours, I would add carpet and mid-ground plants and not have bare open sand for those Cories.

 

[mort]

It seems counter intuitive but the more cover fish have, the bolder they tend to be. This is because they feel secure in the knowledge they can go to ground when they need to and don't have to go far to do so. As I look at your tank it does look very sparse and I'd echo the above advice of adding more plants for cover before trying anything else. You could add some botanicals and this is a great time of year to find oak, beech or hornbeam leaves.
It's also worth giving them a little more time to settle down as the move wasn't long ago and they are a skittish fish.

 

[frothhelmet]

Ooo mort with the habrosus avatar. I best listen Problem is I like the clean look. I do it because it keeps my maintenance low. But, I duly have taken your advice and have now added a little rock cave under the bigger driftwood cave. My habrosus are all about it. Let's see if it makes them bolder in a few days - spooked them building it a bit. Here is what it looks like - great suggestion by the way!!! Sorry the image quality isn't the greatest, but you can see the rock overhang I made and a cory (blurry blob) already sitting under it on the bottom.

 

[Dr Mike Oxgreen]

I have three C. pygmaeus in my heavily-planted 25 litre tank. Initially they were very nervous and I was worried that the group was too small, but they settled after a few days and seem happy now. Even so, they always react when I approach the tank, swimming away initially but returning after a few moments. This is in contrast to other larger corries that I've kept in the past, which have always seemed totally oblivious to any movement outside the tank. I wonder if these dwarf species have better eyesight than the larger species?

 

[lilirose]

I have three C. pygmaeus in my heavily-planted 25 litre tank. Initially they were very nervous and I was worried that the group was too small, but they settled after a few days and seem happy now. Even so, they always react when I approach the tank, swimming away initially but returning after a few moments. This is in contrast to other larger corries that I've kept in the past, which have always seemed totally oblivious to any movement outside the tank. I wonder if these dwarf species have better eyesight than the larger species?

C. Pygmaeus are a shoaling fish- a group of only three are likely to remain far more shy than a group of eight or more.

I have 16 in my heavily planted 90 liter and they are the life of the tank.

 

[Aqua360]

I've been after Habrosus for a while, wish I'd nabbed some the last time I seen them!