Do you think it would be possible

[RobertK]

Totally hypothetical question, not thinking of doing it just curious thats all.

Do you think it would be possible to set up say a 40 gallon tank, stock it to about its optimum capicity, and run it succesfully with no filtration other then water changes and syphoning debris from the tank?

No especially hardy fish, just fish you would normally find at your LFS

 

[WILDER]

They would be fighting for 02 being overstocked, how will you have 02 in the water without a filter.

 

[pica_nuttalli]

depends on what you mean by "optimum".

my concern would be getting enough oxygen in there with no surface agitation. since most freshwater fish come from areas with a fair amount current, you'd definitely have to do some serious research on your stock.

way back in the first weeks i joined, there was a thread with a link to a guy who just doesn't believe in filters. i read the article and questioned some of his claims, but as i'm learning more about the hobby and how the biological processes work in the aquarium... i'm starting to rethink the idea.

definitely would need an incredible amount of planting to handle the ammonia/nitrite/nitrate issue.

--EDIT--
O2 interchanges at the surface whether or not you have a filter. its just that most filters agitate the surface of the water, increasing the surface area and thereby the rate of oxygen exchange. O2 exchage occurs even without filtration, its just at a significantly reduced rate.

 

[Undawada]

There is a school of fishkeepers who practice "Natural Fishkeeping". Generally these fishkeepers don't use any filters at all, pretty much what you were asking. There are completely differet rules for keeping fish this way, you stock far far less than you would normally, and have to have lots of plants, etc.

NaturalAquariums.com