Fish staying on one side of the tank

[Regen311]

Sorry for posting so many questions lately, there just seem to be a lot of weird things going on with my fish lately.

Since I set up my 55 gallon tank (a month or so ago), I've noticed that my fish always stay on the side of the tank where the filter (Penguin 350 from my old 20 gallon tank) is. Some of the bottom dwellers, particularly the loaches (yoyo) will swim all over the place, and the cories as well, and I guess the danios too, but the platys and gold barbs stay almost exclusively on teh one side of the tank. It's kind of funny, because those are all my mid-level swimming fish, so sometimes it makes that side of the tank look a bit crowded, while the other side is like a ghost town.

There are heaters on both sides of the tank, so it can't be water temperature. Ammonia has been 0, nitrites and nitrates in check as well. The only thing I could think is that the more surface agitation there is on that side causes more oxygen to be in the water on that side? But the scientist in me tells me that the water would diffuse throughout the tank no matter what, and the fish that do go over there have no problem at all. Also, the baby platys that have survived are congragating in the water spites I have floating over there, and they're alive and happy.

Here's a picture of the tank:

and the filter is on the left, the "dead zone" is on the right. The blurs are danios. My camera isn't the greatest, and I'm not the greatest at photographing the fish with it. On a side note, I built a bunch of cave type things and rock type structures for my yoyo loaches when I got them, now all the fish seem to enjoy hiding in them more than anything else Oh well, at least they're all happy... I think?

 

[LandGhoti]

Maybe they all like the current from the filter?
Or they've staked out their 'hood. My turquoise rainbows usually hang on only the right side of the tank, except for at feeding time.

I like your caves, and that piece of driftwood on the right (looks like African root?).

 

[Jchillin]

I agree. For unknown reasons, some fish just like hanging out in particular spots. My julii's when resting, just sit on the right rear corner.

 

[Regen311]

Yes, the piece of wood on the right is an africa root. I've never had driftwood in my tank, then one day the mood struck me and I went on ebay and got 2 pieces. I LOVE it (fish do too) especially the other piece, you can't see well in that picture:

It's an amazing piece of driftwood. The "branches" are hollow, which is really cool because teh loaches will go into them, and all the little holes in them let me see them Also, I dug out a bit of gravel underneath it to make a little.. I don't know, it's not a cave, but it's like an under the driftwood area. The barbs have taken that over. They love it (when they're not swimming around)

As far as the caves go, it was a bit of a pain. It's winter, so I couldn't go rock hunting, and rocks are so expensive at the LFS! So I didn't have much to work with... they're also not glued in any way because I'm too indecisive. So I had to basically pick out the perfect rocks that would be the right heights, make sure they were supported so it wouldn't crash, but it's worth it. My fish seem to love it! The loaches swim in and out of them all day. The Danios even will swim down and swim around in them, very quickly of course, but nothing they do seems to be slow

 

[neilanh]

My fish are like that too, at least a lot of them. I do believe it has to do with the currents in the tank. They find a place that they like and that becomes their hang out.