There are many different kinds of filters available in local fish stores. The best kind for you depends on the size of your tank and the needs of your fish and plants.

A popular option is the biofilter 3 in 1. It contains mesh to stop large particles from flowing through, carbon to absorb the chemicals in the water, and it also provides places for large amounts of beneficial bacteria to grow in. These kinds of filters often have a relatively moderate flow of water, not damaging most plants or fish.

Some fish, however, like bettas and almost all fish fry need a more gentle filter. These can also be purchased at most local fish stores. You can get one that looks like this:

Another option to slow the current and stop larger items (like fry) from being sucked into the filter intake is a filter sponge. A filter sponge is a small piece of sponge that has no chemicals in it that you place over the filter intake. It can grow a lot of beneficial bacteria. Be sure not to buy a sponge with soap already added from the grocery store.

Another kind of filter has rotating wheels on the top to move the water flow. Be careful with this kind if you have loaches. If they swim into it, their long bodies may get chopped in half.