Many people remove the filters from small tanks because the current distresses the betta so badly. Here is a way to keep your filter and a happy betta too!! This is not my idea, but was copied from http://www.petfish.net/articles/Do-It-Your...currentkill.php . I personally have not tried this, as all of my males live in unfiltered tanks, but have heard nothing but praise from the people who have tried it!!!



Filter Currents: A Betta's Worst Nightmare

Aquarium Supplies
Many people need some way to slow down the current of a filter, whether because their fish are being thrown around in it or because their betta, a species notorious for their hatred of water currents, despised it. I have had the same problem, and designed a system to help alleviate it.
Stopping the spectre
The vast majority of filters sold in the US are of the Hang-on-Back type. These typically have a 'waterfall-outlet,' where the water falls down out of the filter into the tank. The obvious problem is that as the water falls from the outlet, it accelerates under the force of gravity until it reaches the waterline, then creating a strong current.

The secret to stopping the current is to simply obstruct it. The most efficient way to do this is to use the body of a half-liter soda bottle. I will now describe how to construct the device.

Step 1: Start the incision...



You must first cut the soda bottle appropriately to prepare it for mounting. On the right, you will see a diagram for the first cuts, labelled "Cut 1." You must remove the two ends of the bottle, leaving only a smooth cylinder from the center of the bottle. Next, you need to tear off the label and cut the cylinder along its length, right next to the strip of glue, as shown in diagram "Cut2." You should now have a simple sheet of curled-up plastic.

Step 2: Duct Tape and BubbleGum



This step is very simple: simply tape one end of your plastic sheet - the end with the glue on it - to the top of the filter, and bring the other end around under the outflow, as pictured at left. (I outlined the edge of the sheet so you can tell where it goes) Then you're done, go play in traffic or something.

I use a disposable red plastic cup, cut in half. It works okay, but the soda bottle would definitely work better because it will wrap further around the filter output.
Good idea to add this! :)

Great idea bettas4me! ;)

I'm using this on 3 of my betta tanks. It works great.

My bettas have never had issues with current, but I did get them used to it slowly over a long period of time out of the cup to get their muscles built up. I do keep turnover at 4x or less which at my house is low flow (most other tanks are 10-40x turnover).
Now, my girlies like to get "betta massages" and often continuously "surf" in the current for a hour or longer on end. You'd think it was blowing them around, the way they let it fling them through the tank. Till you see them get to the end of the current and quick, fast, and in a hurry back to the output of the filter, to ride the waves again

However, if your bettas aren't dealing with currents, this is a good thing.

Another idea is to just have plants breaking up the current there.