The filter and the heating of my aquarium do not work anymore. After trying to solve the problem, I've concluded that the only way to solve the problem is to buy a new filter and a new heating. Can my fish (Xiphophorus maculatus) stay alive during about 12 hours (the time I have to wait until the stores can re-open in my city) without any filter or heating?

My house temperature is 23° C, tank has a volume of 100 liters, I have about 10 fish (without the babies).


5 Answers 5


Depending upon the type of fish, it may be possible. Some fish are able to survive in a bit cooler water. However, there are some fish that are extremely sensitive to temperature, for example angelfish are very sensitive, and I don't think they would survive. I have had fish such as guppies and neon tetras that were able to survive for a couple days without a heater. It really depends on the fish. As for the filter, I think they should be capable of surviving for 12 hours without one.


The filter shouldn't matter. A proper setup shouldn't build up anything harmful that quickly. I realize that's a loaded assumption, but with a crazily out of whack bio-load, I doubt even a good filter would keep everyone safe. However, most types of filters do have the added benefit of increasing oxygen exchange. Again, that's something that under most conditions won't rapidly fluctuate if everything else is in order.

However, tropical fish are pretty sensitive to rapid temperature swings. The larger your volume of water (and less surface area), the slower your tank's heat will change. Obviously the closer the surrounding atmosphere's heat to your tank's ideal temperature will reduce risk.


How long the fish can stay without filtration would depend on the size of the tank and the bioload of the fish. The bioload of the tank depends on the number of fish and the size of the fish. For instance, a goldfish will create more bioload than a guppy.

If you have a large tank and a small bioload. The tank can remain without filtration for many weeks.

As for heating, this depends on the ambient temperature of the room which depends on the season and the location. It is better to monitor the temperature with the help of a thermometer.

Fish, being cold-blooded animals, are very sensitive to temperature. Any temperature beyond the acceptable range will affect the fish very fast.



I recently had a power outage for three days. I added warm water to the tank every few hours for the first day, until I ran out of water. When the power came back on, I had four silver dollars about 3" long laying at the bottom of the tank. I went to scoop out what I thought were dead fish and they all started swimming, one upside down but moving. I placed another heater in the tank to warm it up faster, as the temp had dropped from 75 °F to 52 °F (from 24 °C to 11 °C). Within two hours all the fish were behaving normally, eating and swimming.


Platies and swordtails are OK down to about 55 F , 12 C . Mollies danios and paradise fish Ok to about 50 F, 10 C. But they don't do well at these low temperatures . They survive for over about 3 months ( winter) at the low temperatures. I do not run a filter in cold weather .

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