Smaller tetras hiding/staying only in one area of the tank?

[B1gJ4k3]

My main display tank is a 125 planted community tank that's been setup for about 3 months. It looks like this (with some minor additions/rearranging). Stocking is as follows:

• 13-ish Red Wag Platies
• 20-ish Neon Tetras
• 11 Rummy Nose Tetras
• 20 Colombian Tetras
• 8 Boesemani Randowfish
• 4 Albino Bristlenose Plecos
• 4-ish Panda Corys
• 1 Dalmatian Molly
• 1 Amatitlania Nanolutea (A peaceful community cichild that I've heard called a "Gold Convict")

I've recently noticed that the Neon and Rummynose Tetras all kind of congregate in one area of the tank and don't venture too far outside that area, even though they have an entire 6ft tank to swim in. The Neons stay pretty much in the pearlweed under the curved log on the right hand side and the Rummynose pretty much stay in the front right corner in front of the log on the bottom. They come out normally to eat and everything, but otherwise seem to spend their time in those two areas. I'm not positive that either one of them were all that active before, but I definitely remember the Rummynose going back and forth across the whole tank quite a bit. I had a Neon die on me the other day and I'm hoping it was just a fluke and not a matter of stress.

My first instinct is to say that they're being bullied and forced into that area, but I really don't know who the culprit would be. The most recent additions are the Rainbows/Plecos about 2 weeks ago and the Colombians about 4 weeks ago. It's my understanding that Rainbows are super peaceful and shouldn't bother anyone. Colombians can have a reputation for being a bit nippy, but I've never observed any of this behavior and they should all be from similar geographic regions and should be compatible. The Gold Convict is very peaceful and I've never seen him messing with anyone.

Is it just a matter of plant cover or an area to feel safe? Is it a matter of light? I have very dim lights that are on most of the day and then a brighter plant light that turns on for 4 hours a day in the afternoon, but I've never noticed a difference in behavior in lights on/lights off times.

What would anyone recommend as a course of action? I have several other thanks that are empty that I could pull some out and throw into if I needed to, but honestly, I'd rather use those as originally planned. Anybody have any insight here?

[Guppysnail]

Plants will help. Check/change your flow direction and intensity lowered. If they are constantly struggling to swim/fighting the current they will spend time where they need to expend the least amount of energy. 

Edited October 25, 2021 by Guppysnail
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[zestygrappy]

I have cardinal and ember tetras in a community tank and they used to stay hidden around plants. Since I've put some water spangles in, they became way more active. 

So I guess adding more plants should do the trick, if floating plants don't bother you water spangles would be a good choice as they don't grow roots all the way down to bottom of the tank. You would have to scoop them out from time to time as they do form new shoots real quick. 

[B1gJ4k3]

I think it’s definitely a flow thing. I turned the flow on the filter way down and they’ve been much more adventurous. They still aren’t too interested in the more lightly-planted areas of the tank. I guess I’ll just have to go nuts with some plants…😄

[Tanked]

On 10/27/2021 at 11:22 PM, B1gJ4k3 said:

I think it’s definitely a flow thing. I turned the flow on the filter way down and they’ve been much more adventurous. They still aren’t too interested in the more lightly-planted areas of the tank. I guess I’ll just have to go nuts with some plants…😄

Assuming that the convict is peaceful, than changing the flow sounds like a reasonable first step. My tetras enjoy swimming into a gentle flow occasionally. Very briefly adding a circulation pump to the aquarium caused them to seek shelter. My community tank also requires a fish fence in order to keep the Silver Dollars away from the live plants.  As the plants have matured, the tetras have spent increasing amounts of time there.