So I just wanted to post up a quick note here about the huge success I've had with my Koralia 2. My tank is still fairly new and it consists of danios, swordtails, weather loaches, a bristlenose and some ghost shrimp. I've had a pretty good flow by putting the HOB
filter at one end and some bubblers at the other which sort of caused the water to circulate around and my thinking was that even though all the fish I have prefer a good current any of the ones I was buying would be generations removed from the wild so they wouldn't really care. A week ago I put in 2 standard colored weather loaches (Eelvis and Hank Whiskers Jr.) and 1 gold dojo (Loretta Finn) and I have barely seen them since. Loretta comes out to eat and I've seen glimpses of Hank but that's about it. A couple times I actually went through flipping rocks looking for Eelvis' corpse only to find him hiding somewhere. I know they come out at night because I can see their silhouettes when I'm in bed at night.
Well just yesterday I got a Koralia 2 as part of a birthday present and put it in. I set it up in such a way that it's at the back corner on the far right side and is pointed to the center of the front of the tank fairly close to the bottom. There's a nice big chunk of driftwood in middle of the tank so it allows calm spots/eddies in the tank, which is a 50 gallon btw. Anyways, at first I was worried because all the fish seemed to stay on the far left side of the tank but I left it running. Within a few hours I noticed that the danios and swordtails were swimming up the current then letting themselves drift across the tank and really seemed to be enjoying the new current. Then a little later I saw Loretta was out and swimming around in a way I've never seen before, she was all over the place riding on the current and swimming into it. Then the biggest suprise was this morning when I did the feeding, Hank and Eelvis actually came out when the shrimp pellets went in the water. They hid behind a rock in such a position that the current was pushing the food over to them and they more or less just sat there grazing. That was the most activity I've seen out of them since I put them in.
So long story short, if you have fish that are described as ones that like a good current, get them one. It seems to have totally changed my tank for the better in less than 24 hours.