Help with shy cories

[TravisN]

First, stats:

Tank

• Planted 40g breeder estblished early October 2021 (first fish added mid-November)
• Located in my office where I sit at my desk about 6 feet from it all day long most days. Room is usually pretty quiet.
• pool filter sand substrate layered on top of some aquasoil and gravel
• Oase BioMaster Thermo 250 (I know it's overkill)
• NICREW SkyLED Plus Aquarium Light

Stock:

• 7 corydora punctatus
• 2 otocinclus (bought 4, two died)
• 12 leopard danios
• 4 cherry shrimp
• lots of plants

Tank parameters:

• 75F
• pH 7
• 0 ammonia
• 0 nitrites
• ~25 nitrates (usually between 20-50)
• Weekly ~30-40% water changes
• Currently fighting off a bit of an algae issue

Feeding
daily pinch of xtreme krill flakes for the danios and sinking pellets for the cories
occasionally frozen brine shrimp or frozen blood worms 

Hello! Looking to get some help on my first real aquarium. I did research for months before buying anything and ran with only plants for weeks before buying fish, making sure my cycle was established.  

The Problem

My problem is the cories which I bought 8 of back in November (have lost 1 since). The reason I got them is because I thought they'd be active and fun to watch. The first week or so I got them, they did what I would have expected, hanging around together, glass surfing every once in a while. But within a month they became very very shy and have remained that way.

They stay in the back behind the rocks and among the plants all day long until it is completely dark. I mean the sun is set, the aquarium light is off, and all of the lights in the room are off. If I come into the dark room with a dim light to try to check on them, they may hang around for a few seconds, but most of them will quickly dart to the back and hide. In addition to that, they're terrified of me. If I'm at all close to the tank and looking in, sometimes I'll see one that's in the back dart away to somewhere more hidden. And sometimes when I do a water change, if I do anything to scare them, sometimes one of them will completely freak out and swim for their life all over the tank.

Things I've tried, with seemingly no effect:

• I had hoped adding the danios would help them gain confidence, but it did not
• dimming the aquarium light or leaving it off during the day
• changing to a horizontal spray bar
• changing to a vertical spray bar
• lowering the flow
• raising the flow
• feeding them at different times of the day and in different places in the tank

Is there anything else I can do? I was really excited to get what I thought were going to be really active, fun fish, so it's disappointing that I hardly see them. In addition I'm worried that this behavior is because there's something about the tank that isn't good for them.
 

Edited May 6, 2022 by TravisN

[Tihshho]

Adding flow to the open areas of the tank would have been my recommendation. Did you try increasing flow with a powerhead? 

Some cory species can be reclusive. Not all Corydoras from my experience are glass surfers or ok with being out in the open. I've not kept C. Punctatus, so I don't have personal experience with them. Per some breeders videos I've seen of various Corydoras, tanks look empty until food is introduced, to which they come out of hiding. 

[sumplkrum]

I'd say more corys.

It's not like the tank is overcrowded, so another eight couldn't hurt. The more there are, the more you'll see them.

[TravisN]

On 5/6/2022 at 11:39 AM, Tihshho said:

Adding flow to the open areas of the tank would have been my recommendation. Did you try increasing flow with a powerhead? 

Some cory species can be reclusive. Not all Corydoras from my experience are glass surfers or ok with being out in the open. I've not kept C. Punctatus, so I don't have personal experience with them. Per some breeders videos I've seen of various Corydoras, tanks look empty until food is introduced, to which they come out of hiding. 

Thanks for the input. I haven't tried increasing flow with a powerhead or in the front of the tank specifically. I may give that a shot when I do my water change later today. 

 

On 5/6/2022 at 11:55 AM, sumplkrum said:

I'd say more corys.

It's not like the tank is overcrowded, so another eight couldn't hurt. The more there are, the more you'll see them.

Thank you, I've thought about that as well. Are you recommending 8 of the same species or a different species? 

[sumplkrum]

On 5/6/2022 at 12:04 PM, TravisN said:

Thank you, I've thought about that as well. Are you recommending 8 of the same species or a different species? 

That would be your choice. As long as basic needs are met, the fish won't care.

If you like the breed you have, more will be more.

If you want something that's a change of color or maybe less shy, mix in a new school of something else.

[Bev C]

  When I got my community tank  I had more cories and black skirt tetra then i have now  the more cories you have  the better  thy feel more comfortable and they do better with a large school of the same kind of cories   but i use to have 20 cories I had 10 of each juli and panda cories   and  they was fine  they love the water flow in my tank ,,,  My tank  has very old fish and I am not trying to not get new fish yetI am down to 7-8 cories but when i do get new fish I will differentlyget  lots more cories 

Edited May 6, 2022 by Bev C

[Kurt Brutting]

I have 13 Panda Cory’s in my 40 breeder and they like to hide until it’s dinner time. Their offspring is happy go lucky all over the tank exploring digging through the sand searching for food all day long. 

 

The 1st generation is spoiled with 2 many hiding spots. Maybe when yours has fry they will be braver. 

[nabokovfan87]

On 5/6/2022 at 8:28 AM, TravisN said:

They stay in the back behind the rocks and among the plants all day long until it is completely dark. I mean the sun is set, the aquarium light is off, and all of the lights in the room are off. If I come into the dark room with a dim light to try to check on them, they may hang around for a few seconds, but most of them will quickly dart to the back and hide. In addition to that, they're terrified of me. If I'm at all close to the tank and looking in, sometimes I'll see one that's in the back dart away to somewhere more hidden. And sometimes when I do a water change, if I do anything to scare them, sometimes one of them will completely freak out and swim for their life all over the tank.

I think I have a challenge for you....

The next time you walk into the room and your shadow scares the fish and you see them run off to another part of the tank, try to find out where they go to.  Do they go to a hide behind a rock or simply the furthest spot from where you're at in the tank?  Do they tend to keep a piece of the hardscape between you and themselves?  I think the corys are doing exactly what comes natural to them.  When I look at the tank you have I do see rocks, but I don't see cover. Some corys really just LOVE to have cover. They want to feel protected from things and that gives them the security.

If this is the case, then I recommend testing them.  Walk into the room, sit down in a chair 3-4 feet away from the tank and watch.  After they scatter you should see some of them pop back up and explore the tank, to try to look at you, some sort of a reaction.  There is a very famous cory breeder who's mantra is "be the fish" and right now that's what comes to mind.  They are trying to explain a need to you, just give them a chance to see what exactly that is. 

Here is some of mine, I will go take photos and show you the difference between open / covered water.   These guys are FINALLY getting their new tank here shortly, so I'm excited to give them a new setup.  They've been in this holding tank for FAR too long and it's been a mess the entire time because of the load.

To be clear.... you see a few of the corys. There's 20+ that you don't see.

[TravisN]

On 5/7/2022 at 3:20 AM, nabokovfan87 said:

The next time you walk into the room and your shadow scares the fish and you see them run off to another part of the tank, try to find out where they go to.  Do they go to a hide behind a rock or simply the furthest spot from where you're at in the tank?  Do they tend to keep a piece of the hardscape between you and themselves?  

That's a good point. They definitely are running for cover, not just "away". Sometimes they'll try to wedge under a rock or something. I say they go to the back, but that is also behind hardscape and under the most densely planted part of the tank where the pogostemon stellatus octopus is growing wild. 

[ShySnail]

I second what @nabokovfan87 said about providing more cover. While my pandas weren't as shy as your cories, when I added a ton of leaf litter to the tank that is large enough for them to hide under, they were much more willing to be out and about.

Edited May 7, 2022 by ShySnail
Typos

[Bev C]

yes they love hiding places for sure i have plenty of rock, plants , wood , & sponge  filters to hide 

[TravisN]

So over the weekend I moved my spray bar toward the front of the tank which I believe increased the flow in the front, decreased the flow in the back, and also reversed the flow in the tank from clockwise to counterclockwise as you're looking down into it. This has changed the behavior of the fight a bit I think. The danios like swimming against the current or turning and gliding with it in the front of the tank. 

I have noticed a little more activity from the cories that I think this is contributing to. They're still skittish and hide in the back during the day, but I see them pop out in to the back center of the tank every once in a while for very brief periods of time. I think it's partially due to the danios swimming down where they hang out and chasing them around a bit. It's not a lot, but is more often than I saw them before.