How do you keep fish alive without a filter?
Tips for Maintaining an Unfiltered Tank
For example, live aquarium plants will act as filters by converting the CO2 produced by your fish into the oxygen they need to breathe. Having plenty of live plants in your unfiltered tank will help to keep the water quality in your tank high enough for your fish to survive.
Do fish actually need a filter?
All fish tanks MUST have biological filtration; biological filtration is the cheapest, most efficient and most stable way to breakdown toxic ammonia. Mechanical filtration traps such particles as plant leaves, uneaten food, etc., allowing them to be removed from the tank before they decompose into ammonia.
How long can fish survive without air pump?
An aquarium fish can stay up to two days without oxygen (in still water) but they still need some more amount of oxygen to breathe and do their essential daily work.