5 Reasons Why Betta Fish Need A Filter

If you look up care info for a betta fish, there is a lot of conflicting information. Some people say that betta fish do need a filter, while others say that betta fish prefer still water. The truth is, both are correct. Betta fish need a filter, but they need a low-flow filter (one that doesn’t have a strong current). Here are 5 BIG reasons why a filter is so important:

  1. Ammonia. The number one cause of death among aquarium fish is ammonia, which is caused by the build-up of food debris and fish poop in the water. A filter allows for the growth of beneficial bacteria that eat the ammonia, keeping it at safe levels.
  2. Less Water Changes. Because a filter takes care of the ammonia, you are able to do water changes less frequently. When Finley was in a 2.5 gallon tank without a filter, the water needed to be changed every 6 days. I know that because of the Ammonia Alert Guage that I keep in his tank (made by Seachem). With a filter, he only needs a water change every 3 weeks or so, which removes the nitrate and nitrite (by-products of ammonia). If you don’t know about the nitrogen cycle, here is a really easy picture guide here on FishkeepingAdvice.com.
  3. Cleaning. You may think this one goes into point #2, but it doesn’t. The reason that we got a filter in the first place is because Finley got some mold in his tank that I simply was not able to get rid of (despite drastic attempts, which you can read about in the post: Dealing With Mold in a Betta Fish Tank). The filter removed the mold debris floating in the water. It also removes anything else that floats around in the tank sometimes like dust or cat hair. Having a filter keeps the water looking crystal clear.
  4. Oxygen. Before getting a filter, Finley mostly breathed air using his labyrinth organ. Every two minutes he needed to surface to take a breath. That must have been exhausting for the poor guy. After getting a filter, Finley only takes a breath a couple times per hour. A filter helps to oxygenate the water, which allows it to be easier for him to ‘breathe’ using his gills.
  5. The Current. I have read in many articles on the web that betta fish prefer still water. Maybe I just have a weird little bettas, but both of mine like the current. When I pour water into their tanks during a water change, I do so slowly because otherwise the gravel and decor go flying, and they both always swim over and play in the flowing water. I noticed that long before I ever got a filter. Now they both swim over to play in the filter current sometimes, Findee does this often – she uses the current like an endless pool, swimming against it so she stays in place but gets lots of exercise. There is a small caveat to that though – it has to be a low-flow filter. When I was cleaning Finley’s tank one time, I accidentally flipped it to the high setting and when he came out of his cave near the filter, he could barely swim because the current was so strong. The same thing happened with Findee – I accidentally flipped the filter to fast flow, the difference wasn’t noticible to me, but she was not happy about it, she seemed a bit ill actually, almost seasick, which is why I figured out what was wrong. The low setting is fine for them though. Finley also likes that it makes his food swirl around on the surface of the water – makes it more like it would be in the wild.

Types of Filters

There are two main types of filters: Cartridge Filters and Media Filters.

A cartridge filter is exactly what it sounds line: a filter with a cartridge that is usually filled with charcoal and occassionally some other water cleaning products as well like zeolite. These are the same types of filters that are used in sink faucet filters or a Britta water pitcher in the fridge. They need to be changed regularly, usually every 3 months unless they get dirty from algae or something else. The charcoal and zeolite are highly absorbent, so they soak up all the bad things in the water, therefore removing them. However, once they have soaked up all they can, they obviously stop working, which is why the cartridge needs to be replaced. One of the benefits of using a cartridge filter is that it removes impurities from the water that are not aquarium-related, just the regular water impurities that are why humans use filters (heavy metals, contaminants, etc.).

A media filter works by moving the water through media, which usually is a sponge, and over time, beneficial bacteria grow on the sponge and work to clean the water by eating up all the waste products you don’t want in the water (ammonia, nitrates, nitrites). The benefit of using this type of filter is that you never hae to change it unless your fish gets sick and you want to disinfect your tank. The bacteria grow naturally in a process known as “cycling the tank” – as the nitrogen cycle takes place naturally, the bacteria numbers grow as needed to deal with the waste and finally (after about 2 weeks) they will achieve the perfect level for keeping the tank clean. There are bacteria products you can buy to add the bacteria to the tank and hasten the process, but this isn’t necessary. The only downside is that there can be spikes of ammonia during the cycling process (the first two weeks), which can be deadly for the fish, so it’s important to do extra water changes while the tank is cycling to protect your tank inhabitants.

What filter do my bettas have?

Finkey had a Whisper cartridge filter with a bottom intake and a speed setting. I haven’t been able to find the exact same one to tell you the model number, not even on the Tetra website. It came with the Aqua Culture tank set that I got at Walmart, so maybe that’s the only way it’s sold. However, there are many filters sold with these same features.

Baby Findee got a media filter with a spray bar that also has a flow adjuster. It’s a Tom Pet Products Internal Filter tshown in the Amazon ad below, although mine is black and it now appears to come in blue. It’s the perfect size for her little 2.5 gallon nursery tank and I love the adjustable spray bar – it can be rotated any direction to optimize how it fits with your tank setup. Findee absolutely loves the spray bar too – because it reaches out over the open water in her tank, she uses it as an endless pool (she swims against the current, which give her a great workout even though she’s really just swimming in place.) She does this so often that I call her my little Olympian. This filter is good for tanks 1-10 gallons. (As an Amazon Affiliate, I may earn from qualifying purchases.)

If you want to get a filter for your betta, here are things a betta fish filter must have:

  • a covered intake (bars, etc.) so that they can’t get sucked up into it (most have this already, but make sure – some don’t)
  • a high/low speed setting so you can set it to low
  • the right amount of power for your tank size (gallons – it will say on the box what size tank the filter is for) – A smaller filter doesn’t have the strength to process large amounts of water, and a larger filter is too strong for a smaller tank, especially one with a betta fish in it.

Feeding Concerns

I was very concerned when getting a filter that Finley wouldn’t be able to eat as well with the water surface moving. As I have said, it turned out the opposite: he loved chasing around the pellets. However, they can move into the filter stream if he doesn’t get them fast enough and then sink. If you don’t always have time to feed your betta a couple pellets at a time, then wait until he eats them before giving more, a betta feeding ring might help prevent the pellets from getting into the filter stream. I don’t have one myself, but I’ve thought about getting one. Below is a link to the product on Amazon. (As an Amazon Affiliate, I may earn from qualifying purchases.)

Both Finley and Findee gave their filters two fins up!

Here is a video of when Finley decided to build a nest right in front of the filter outflow:

Happy Filtering!


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