Anything small I can keep without a filter?

I am searching for any aquatic animal to keep without a filter! Thanks!

A number of fish and aquatic vertebrates (amphibians and such) can be very healthy without a filter--but it takes a good deal of understanding of the needs of the fish/amphibian, and involves regular maintenance just like any aquarium but geared to the specific environment.

Shrimp maybe?

Tank size, planting, temperature... all of these things are as important if you want an informed answer.

I have tried a few neocardinia shrimp without a filter for a few months and they have done well (bred). I don't have a heater either so will put them back (the ones I can catch lol!) in the community tank for the winter. I think live plants are essential.

pest snails, shrimp, macro-organisms (water bugs ), and other types of non pest snails

I have 1 self-sustaining patio pond (42g) and 1 self-sustains patio tank (55g). I have kept rosy barbs, Mosquitofish, flagfish, platys, and many species of snail. These tanks must have access to the sun, as algae is the main filter. You must have a forest of plants (I use anacharis and coontail, though I have 5 other species in each tank). The sun keeps it so that hair algae can grow. I do trimonthly water changes.



If you want to keep it indoors, which I assume you do, you simply have anacharis, hornwort, or a different free-floating plant (I recommend washing it in part hydrogen peroxide part water mix before adding). This will act as the main filter. If you add American Flagfish, they will keep the hair algae down. Flagfish are arguably the hardiest fish species out there, and they are not hard to please. I recommend an unheated tank, assuming weather permits.

If you want something super simple, a little 2.5g tank can hold a couple Neocardinia shrimp. I am raising a couple dragonfly nymphs as well. Super easy and hardy.

Here is a 4ft long tank from the side. This isn’t after a water change. The water tends to have a greenish tinge, as it is in part sun. The anacharis seasonally dies down. The fish in this tank slow their metabolism in the wild down as it gets cold, so it works out perfectly.



Let me know if you have any questions. I have kept these tanks for around 2 years, and they are not only succeeding, but thriving. My Gymnogeophagus Terrapurpurra have bred, as well as the flagfish, rosy barbs, Xiphophorus, and Mosquitofish.

I'd just stick with a lovely looking shrimp, breeding them to sell or get store credit from your LFS. Something like Crystal shrimp perhaps.

Filters are great. However they don't do as much as most people think. All they really do is collect organic waste where it continues to decompose and pollute the water. Granted, filters make the water look more clear, but not more pure. As previously stated, you need to do regular routine partial water changes in order to keep the water safe for our aquatic pets. I hope this helps. Best of luck.

Footnote: The Dirty Truth About Filters

Here is a current picture of my 55g. The water isn’t dirty, the camera changes the pigment of the water. It has a green tinge.