How Long Can Fish Go Without Filter?

Sam Livingston
  • #1
I'm on vacation until Thursday and got call from grandapa who is taking care of my fish while I'm gone saying that storm knocked the power out. How long can the fish last without the filter pumping oxygen into the tank?
  • #2
They can actually last for a long time without a filter, During December, we had a horrible storm that knocked out the power for about 8-12 hours and there were no dead fish in the entire tank.
  • #3
Theoretically, the beneficial bacteria start dying off after about 30 minutes without oxygen (oxygen is supplied to them through filtration, so when filter is off, they have no oxygen). But, I've had my tank without electricity for at least 24 hours during a power outage. And nothing bad happened to my fish. I measured Ammonia and Nitrite after the power outage and they were at 0, so that means I didn't loose my nitrifying bacteria. Or if I lost them, I didn't loose enough to cause a mini-cycle.

Also, it's better if the power outage happens to be in the summer because then tank water temperature can be warm without a heater. But in the winter, the temp. of a tank can be too low without heating in your house (since your tank heater is not working during a power outage).
  • #4
That brings up a point I have wondered about...I am fairly new to the fish hobby (and I think already an addict)...Prior to me having my fish tank we had some power outages here last power went out for three days in the winter and then 4 days in the summer...was a bad year here...
I am just wondering if there is some sort of backup power supply for fish filters and heaters? I don't have a backup generator...and frankly I don't think I am "technically advanced" enough to know how to hook up a generator even if I did have one. But is there a "generator" that is for fish tanks?
  • #5
power generators aren't difficult at all to use I live in Florida and am always left without power on account of hurricanes but there also is a battery powered air pump that will keep the water oxygenated. also if its cold and power goes out wrap blankets around your tank to keep heat in and it will also slow the fish's metabolism so they don't use as much energy
  • #6
Another option would a UPS like somepeople use on their computers. They come in many sizes. Just a large battery backup system. Would have to calculate the amps of all important devices and determine the amount of time to be prepared for. UPS = uninterpretable power supply
  • #7
I am going to put this to the test at the end of the year. We're going to move from CalI to Brooklyn, so the tanks will be in an ice chest (excellent insulator - not just for keeping coke chilly) and will run at night when we crash at the hotel. It's hopefully going to just be a 4 day process. I'm a bit worried about the puffer, but we have excellent filters, so all should be well.
  • #8
I have my "fish tank power bar" plugged into my UPS, the line filtering part since I don't have any more outlets for the battery back up but the main reason for using the UPS line filter is that brown outs can fry transformers/motors, so I don't want to take a chance. if the power does go out then I can switch plugs to the power backups, mine will probably last on hour but u can get bigger ones and they are worth it, a **** of a lot cheaper then replacing a power supply ( experience).
  • #9
So that tropical storm is hitting here, pretty hard in fact. The power is getting knocked out all over the place and I am beginning to get a little worried.

How long can fish survive in a tank if the power goes out and the filters stop working?
  • #10
What type of tank is it and what fish are occupying it?
  • #11
It depends on the level of over or under stocking in the tank, whether or not it is overfed, etc.

We do not have filters on most of our tanks, but our tanks are seriously understocked as far as bioload goes.

The only surface disruptions our tanks get is daily feedings and weekly waterchanges. Again, if your tank is overstocked you could disrupt the surface by hand and be fine.
  • #12
Well right now I have a cory cat and a scissortail in a 2.5g minibow (don't flame, I know they shouldn't be in it!) but when I had the mass fish death I threw everything out and moved the two lone survivors into the already cycled 2.5g to await a new set up (and bought another 2.5g minibow to move my betta to. I divided the old water in half and added new water and fiddled around with the filters and cartridges to cycle them).

The death of the previous tank is a long story, but to make it short my 20 gallon sprung a leak in the middle of the night. When we woke up the following morning there was about 2 inches of water left and 8 dead fish. The hard wood floors were destroyed as well. So I'm going to move Fred & Ethel into the 29 gallon once it is set up.

But for now I have 1 2.5 with a betta and 1 2.5 with a scissortail and a cory cat. Whisper Micro Filters.
  • #13
The Betta will be fine for days actually as long as it isn't too hot/cold..........Not sure about the cory.....
  • #14
We have had a betta splenden in a 3g, in the past, with no filtration and done just fine with no surface disruption other than daily feedings and weekly waterchanges.

The cory and scissortail should be about the same.

Hehe. I've been ninja'ed twice by the same ninja!
  • #15
Thank you, that makes me feel better.

Now let's keep our fingers crossed the power doesn't go out so I don't have to worry.
  • #16
The fish will be fine....I'm more worried about you lol.....Do you have flashlights ready?
  • #17
Flashlights, candles... stupid tropical storm... I was out this morning and they had the coastal evacuation signs up and they were making announcements about where shelters are located. Kinda scary. They haven't kicked us out yet though.
  • #18
I know the feeling.....We get some nasty monsoon storms here in AZ and it knocks the power out...I've had it blow up a hard drive and almost flood my house when my salt tank sump overflowed....

Stay safe!
  • #19
Please let us know as soon as it is over so that we know all is alright with you.
  • #20
Just wanted to let everyone know that the storm has passed. No damage to my house and no power failures. My boyfriend's power is out though and a few trees fell in the neighborhood, but nothing major.
  • #21
GAH!! I got a new but used fluval 304 for one of my tanks cus the 104 didnt do enough filtration but was also making a rattle. well, this one rattles too. I took it apart over and over. just did it again to check the shape of a part and I SNAPPED PART OF THE IMPELLER!!!! GAH!

how long can they go without filtration, I can't get to the store now, my daughter has a friend here.
  • #22
I'm going to make a guess here that you're talking about the 55 gallon planted. If that's the case, you may not see much damage to the cycle at all. If it's heavily planted, you've got a ton of nitrifying bacteria growing on every plant leaf in the tank. Two of my aquaria have no filtration at all, and I still have no ammonia.
However, you want to keep an eye on the ammonia, and do partial water changes and use Prime (or equivalent) to keep the fish healthy. In particular, the gourami will suffer quickly if exposed to ammonia.
  • #23
If you're going tomorrow you'll be fine. He's talking about his 20 gallon with the 104 fluval filter.

*Edit* She's****
  • #24
Hello Coffeebean. Be sure to keep all of your filter media wet. I would suggest adding it directly into your tank to be on the safe side. That way it will have a food source and oxygen source.
I think you'll be fine as well if you can pick one up tomorrow.
  • #25
I'm talking about my 25 tall. all the media is still in the canister which is full of water. I can go as soon as my daughters playmate is picked up. I turned on the air stone.....I really hope they have the right parts I need!!

this tank has 2 angelfish, 3 long finned rosey barbs, 3swordtails, 5 platies, 4khulI loaches, a baby albino bristlenose (1.5") and a rescue pleco that is being rehabilitated (4")

If you're going tomorrow you'll be fine. He's talking about his 20 gallon with the 104 fluval filter.

ahem. she :-*
  • #26
Alright. The fish should definitely be okay for that short of a time. As Aquarist said, keep the media wet. That's about your only concern.
  • #27
cant you put on one of the ones you were selling for now?
  • #28
If you have a air stone you should be fine... maybe put the cartridge on top of it to give it more oxygen
  • #29
One thing you need to be careful of is if your tank is slightly overstocked. My tank is just a bit in my 55 with a fluval 305.

Since I am slightly overstocked I bought some el-cheapo shrimp as an indicator because in my limited experience when water parameters change for the worse the inverts die very quickly. I woke up one morning and noticed 3 dead shrimp and a tank full of lazy fish. I could not put a finger on it till I looked at my output and noticed nothing was coming out. I looked at my intake hose filter and it was so plugged that it was sucking itself in so I removed it and the filtration started up instantly. I figure that the filter had been plugged for 3 days and I had a spike of nasty (ammonia, phospates or whatever..) that led to the die off.

I immed did a water change put on a new filter cover and all my lazy fish started to be crazy party fishys again.

If you are under or normally stocked I would bet they could live for weeks with no filter depending how much natural filtration you have (ie..plants) but if you are overstocked even slightly you may only have only a few days before things get sour.

What I have also done to help with this situation in the future is get one of those fancy little portable filters as a last resort. Those little guys won't keep the tank fresh but they will keep your fish alive until you can get a fix or a new filter.

  • #30
no where in town HAS the parts I need . know why everywhere has so many fluval parts on the shelves? the wonder of fluval canisters is wearing off...this is the 2nd one now. I should have learned the first time not to buy another one used.

anyways, I replaced with a rena hob filter that has 3 chambers for media so I can still use my fluval media in it. it is rated up to 55 g so that should do for an overstocked 25.
  • #31
Morning CoffeeBean. I had the largest Fluval made a few years ago. Once it bit the dust I didn't buy another one either. It did a great job while it lasted though (even though it wasn't very long) I'm glad you found a new filter.

There is a "reviews" section of the forum if you want to type one up.

  • #32
Here are the details: it's a 55 gallon tank, just set up. The tank was running for 24 hours; I dechlorinated the water and put Stress Zyme in the tank. When I got home with my first 4 fish, the filter was dead, and the store is closed. I did manage to talk to the store, told them the issue, and they will have the fix... in 3 days.

I have somewhere between 4 and 6 inches (definitely less than 6) of fish in the tank: one Angelicus cat, and 3 very small iridescent sharks. With 55 gallons and less than 6 inches of fish I figure I'm safe for a little bit, I'm just wondering how long? I also do have an air bar running, so there is surface disturbance with the tank.

Any information would be greatly appreciated!
  • #33
Your fish should be fine with air running til your parts get in. Of course your cycle must still be completed. Be sure you keep your new filter media moist or out into the tank to save what bit that has started....and keep your regular water changes.
  • #34
Welcome for Fishlore mr3856a! Sorry it's under these circumstances.

As you have air running your water is being aerated, I'd suggest that you do daily water changes with Prime or AmQuel+ as both can help to protect your fish from the ammonia that will be building up with an uncycled tank. You will need to test your water daily to monitor it closely for the health of your fish.

Will you be replacing your filter with the same thing? If so, I'd recommend you add the filter media to your tank near the air stones. This might help to get the bacteria to start to colonize the media, but not that sure if it could help or not.

Good luck with your tank.
  • #35
Your fish will be fine for 3 days but just keep checking up on them and make sure to do frequent water changes
  • #36
My filter just died, I have taken it apart cleaned it changed the fuse and a few other things I have found through Google but the filter is almost definitely broken. I have ordered another one that will arrive tomorrow but I'm worried about the fish. I just performed my water change this morning and fitted an additional air stone so there is lots of surface movement. Has anyone had a filter go off for 24 hours or so? Anything I can do to ensure my tank doesn't die? Any help would be greatly appreciated.
  • #37
I run a canister and 4 sponge filters in my 60g. I tested my water today before my water change and results were 0 across the board. I noted my canister had "slowed down" it's flow. Did my WC, rinsed out the canisters media and pads.
Turned the power back on, nothing came out the outlet. Checked the power outlet. Canister wasn't plugged in and probably hadn't been for a couple of days

Do you use prime? Might be worth giving a dose of prime just to ensure if many ammonia does build
Up the fish will be safe

  • #38
If your tank isn't overstocked, you should be okay. The big thing with the new filter is getting biological filtration established in the media. If your old filter had pads/sponges/ceramic media in it, try and keep the beneficial bacteria alive by immersing it in your tank by one of the airstones to help oxygenated water circulate through. Don't feed your fish for a day - it won't hurt them, will help reduce the bio-load.

A few weeks ago a huge wind storm knocked power out in my area, and I was with no power for 30hrs. My fish survived just fine. I was more concerned about the temperature drop than I was about the lack of filtration.
  • #39
I accidentally unplugged my filter when I was using a spare outlet to charge my phone and didnt realise for 3 days. I didn't lose any of my inhabitants so if its only 24hrs I wouldnt worry.
  • #40
Phew thankyou I have been totally stressing.

So if I connect a new filter tomorrow will this re start my cycle and potentially kill the fish? I'm such a stress head and stress about every little thing haha

Similar Aquarium Threads

  • Locked
Top Bottom