Which Filters and Filtration Devices Are Recommended for Medaka? [Submersible, Sponge Filter, Hang-On-Back]

This article will discuss the best filters and filtration devices for Medaka, including submersible filters, sponge filters, and hang-on-back filters.

What Are the Criteria for Filters Recommended for Medaka?

We’ll explain what makes a filter suitable for medaka.

Should Filters Be Avoided in Medaka Tanks?

There is a notion that filters should not be used in medaka tanks because the water flow can exhaust the fish.

This notion is half wrong and half right. First, medaka do not get exhausted by the water flow from filters. Of course, if the flow is too strong, they may struggle to swim, so it’s advisable to adjust the flow or provide areas of weaker current with plants.

However, a strong flow alone will not cause death.

Not That Filters Shouldn’t Be Used, But They Aren’t Always Necessary

It’s not so much that filters shouldn’t be used with medaka, but rather that they are often unnecessary.

This is because medaka can be kept indoors without filters or aeration.

In fact, I have kept medaka in 30 to 40 cm tanks without filters indoors (though I now use filters in all tanks).

It’s commonly said that “one fish per liter” is sufficient, and I’ve found fewer issues with disease or other problems without filters than with them.

Many people also keep medaka outdoors without aeration. Thus, filters and air pumps are not always necessary for medaka keeping.

Should Air-Lift Systems Be Avoided?

It’s often said that submersible or undergravel filters, which use air-lift systems, should be avoided for medaka because using an air pump promotes the proliferation of aerobic bacteria such as Columnaris.

Indeed, I’ve had cases where stopping the aeration in tanks where medaka were dying off and treating the water halted the deaths.

While goldfish and tropical fish may be fine, medaka are particularly susceptible to bacterial infections, which can be exacerbated by air pumps.

In fact, to test this theory, I set up four tanks: one with aeration, one without, one with a medicated bath and aeration, and one with a medicated bath without aeration. I introduced five medaka into each and observed them for three weeks.

The tank with aeration but no medicated bath had half the fish die, whereas tanks with a medicated bath with or without aeration had no deaths.

From this, I believe that tanks not prone to bacterial infections or those treated with medication can safely use an air pump.

If Properly Treated, Aeration Shouldn’t Be a Problem

However, if proper treatment is administered, aeration should not pose a problem, so I have introduced a sponge filter after adding Aguten and Herbaceous to the tank.

Indeed, having a filter reduces the need for frequent water changes and significantly improves the condition of the fish.

Aguten and similar products are safe for bacteria, snails, and shrimp, allowing for worry-free use.

Aeration Prevents Green Water

Moreover,