How long can fish survive w/o filter?

[Barracuda]

Hi I have a fish that needs to be quarantined, however I am wondering how long it will last if i dont have a filter in the QT tank (i can fit a heater and airstone). If I dont feed it for 3 days, will it survive for this long?

[Old Dave]

If you can provide sufficient regular water changes you don't need a filter.
How often depends on fish size & tank size. Keep the aeration up.
Some more experienced fish keepers can probably give you a percentage if you supply tank details.

How long do you need to maintain quarantine for?
New fish or illness?

I suggest having a sponge filter maturing in a main tank or sump.
Compared to your fish they're cheap!

JMO, HTH,

Old Dave

[Barracuda]

I'm wanting to quarantine and medicate a dwarf gourami - it has developed some sort of red ulcer on it. I'm planning on using a multi-purpose medication (dont these meds kill the beneficial bacteria in the filter?) and leaving it in there for 3 days, so i cant really change the water.
The tank it will be in is a small one, around 6L (something like 27x14x16cm). The fish itself, being a dwarf, is very small so this is more than enough space for it. The only thing is that my sponge filter would be too big for the tank.

[ILLUSN]

you could change the water everyday and just redose the meds.

[Barracuda]

Thanks for all the suggestions.
I have decided not to take the risk, i have put it into a 2ft with a sponge filter. I am now wondering, if the multi purpose med kills the bacteria in the filter, what is the filter doing?

[ILLUSN]

airating the water, maintaing some flow to help with thermal control, mech filtration of uneaten food and small floating waste.