Fish dying at night

[austenreefer]

Have you guys had any experience with fish dying randomly in the middle of the night seemingly for no reason? They always look fine the previous day and then we wake up and they’re dead. We have corals and they’re all fine so the possibility of it being any sort of water parameter seems unlikely. We think it could be lack of oxygen, but that might just be because I’m used to freshwater tanks getting low at night due to plants. Sorry if it’s not much to go on.

 

[Auquanut]

Tell us a little about your tank. How old is it? How big? What kind of filtration? What kind of fish? Does anything live for any period of time, or is it the first night?

 

[Peace River]

Tell us a little about your tank. How old is it? How big? What kind of filtration? What kind of fish? Does anything live for any period of time, or is it the first night?

+1

Also, do you have any inverts or other nocturnal critters in the tank (maybe even ones that hide in the rock or sand)? Some can be opportunistic at night.

 

[austenreefer]

Tell us a little about your tank. How old is it? How big? What kind of filtration? What kind of fish? Does anything live for any period of time, or is it the first night?

The tank is only 3 months old. It is a 30 gallon biocube. We just use live rock as filtration but we use phosgaurd and that other similar product that is slipping my mind in the back just to help with phosphates and nitrates. The 2 that died were clownfish that were paired and died a few nights apart. And yes they lived for the full 3 months until now so that’s why it’s so tough to diagnose.

 

[austenreefer]

+1

Also, do you have any inverts or other nocturnal critters in the tank (maybe even ones that hide in the rock or sand)? Some can be opportunistic at night.

No just blue hermit crabs and snails

 

[Darth.Daddy12]

Test perameters for water would help. As would PH reading from right before lights turn off to right before they turn back on in morning to see how big a swing you might have.

But a mated pair of clowns? That’s not good by itself.. they live through almost anything. I think they got sick with something you didn’t notice. But going to be impossible to tell at this point.

Any other fish still in the tank?

Should also consider adding a shrimp to the tank. Shrimp are very sensitive to water issues and can be a first indicator before something gets out of control enough to kill fish.

 

[austenreefer]

Test perameters for water would help. As would PH reading from right before lights turn off to right before they turn back on in morning to see how big a swing you might have.

But a mated pair of clowns? That’s not good by itself.. they live through almost anything. I think they got sick with something you didn’t notice. But going to be impossible to tell at this point.

Any other fish still in the tank?

Should also consider adding a shrimp to the tank. Shrimp are very sensitive to water issues and can be a first indicator before something gets out of control enough to kill fish.

There are no more fish in the tank. This is my girlfriends tank and my tank has a pair of clownfish and trust me I know how hard they are to kill. I have done some dumb stuff in the process of learning this hobby and they have survived through it all. That’s why her tank absolutely baffles me.

 

[Darth.Daddy12]

There are no more fish in the tank. This is my girlfriends tank and my tank has a pair of clownfish and trust me I know how hard they are to kill. I have done some dumb stuff in the process of learning this hobby and they have survived through it all. That’s why her tank absolutely baffles me.

Yeah I’m not sure there is going to be any answers here other then testing water specifically PH swing..

I think I’d just remove the hermits and snails and med the tank as if it were a QT to be safe and then try again with a shrimp mixed in. I always use shrimp in any tank fresh or salt cause if anything in the water is off they will let you know quickly..

 

[leewish]

How were they acting during the days leading up to their death? Did she notice odd swimming activity or discoloring? If only 2 fish that died a few days apart its not really random.

You also mentioned oxygen levels and a 30g AIO. Was there a wavemaker or just the return pump? Also curious what she was using to check the salinity. Could be some quick evaporation and spiked the salinity?

 

[vetteguy53081]

What is Tank temp and salinity ?
I would do a slight water change focusing on gravel with siphon (to see if anything unusual like a manyis shrimp, fireworm pops out)
Ruling that out, Shoot a water sample to a trusted LFS and have them test some of the critical parameters to assure youre getting proper readings from your test lit and for comparison.

 

[austenreefer]

How were they acting during the days leading up to their death? Did she notice odd swimming activity or discoloring? If only 2 fish that died a few days apart its not really random.

You also mentioned oxygen levels and a 30g AIO. Was there a wavemaker or just the return pump? Also curious what she was using to check the salinity. Could be some quick evaporation and spiked the salinity?

The fish were fine leading up. We have a wave maker as well as a return pump but apparently last night her mom pushed the return pump down and there was little to no surface agitation all night.

 

[leewish]

The fish were fine leading up. We have a wave maker as well as a return pump but apparently last night her mom pushed the return pump down and there was little to no surface agitation all night.

How well versed are her and her mom on the tank? Was it something your gf maintained or were you doing much of it?

 

[King Turkey]

Were you get the live rock? You could have introduced a pest also maybee.. Did you cure it?

 

[Jesterrace]

Do the fish have a sort of copper colored sheen to them when they die? Parasites would be one explanation, but I wouldn't put it past some nasty hitchhiker coming out at night and killing them while they are resting either. Did you use actual live rock or just dry rock and then seeded with bacteria?

 

[HOOPDEEZ]

I would go fallow for a while, don’t add meds to the dt or they will kill corals and bind to your rocks. I would think a parasite is the culprit, but can’t be sure. Any changes made before they died? Water change? New additives?

 

[austenreefer]

How well versed are her and her mom on the tank? Was it something your gf maintained or were you doing much of it?

They know enough to keep it going. But I do a lot of it

 

[austenreefer]

Were you get the live rock? You could have introduced a pest also maybee.. Did you cure it?

I got the rock from my LFS and I trust him with everything so I’m 100% sure the rock is fine

 

[Paul B]

Really hard without a picture of the tank. Normally fish will die in a tank at about three months due to ammonia poisoning. The fish and corals you added too soon for the bacterial population to catch up. This is very common at the 3 month mark.
Ammonia won't show up on a test kit after the fish die because the bacteria will process it pretty fast, just not fast enough to keep the fish alive.

A tank is not instantly cycled as soon as your test kits read there is no more nitrite. That just indicates that you have enough bacteria to take care of a dead shrimp or whatever you used to cycle the tank with.
It takes about 3 months for the bacteria to grow enough to add more than about one small fish.

What did the fish look like as soon as you found them? Did they have their mouths closed or wide open?

They "probably" did not die from parasites as you would have noticed that and fish "never" die from lack of oxygen unless the water was visibly cloudy.

I don't think going fallow is the answer. You need life in there to keep the bacteria multiplying and an empty tank will cause the bacteria you have to die back. The corals don't contribute enough ammonia to keep the cycle going.

I would add one small fish and nothing else for a few weeks. Then if all is well, add another small fish.

Good Luck

 

[Subsea]

Have you guys had any experience with fish dying randomly in the middle of the night seemingly for no reason? They always look fine the previous day and then we wake up and they’re dead. We have corals and they’re all fine so the possibility of it being any sort of water parameter seems unlikely. We think it could be lack of oxygen, but that might just be because I’m used to freshwater tanks getting low at night due to plants. Sorry if it’s not much to go on.

Have you guys had any experience with fish dying randomly in the middle of the night seemingly for no reason? They always look fine the previous day and then we wake up and they’re dead. We have corals and they’re all fine so the possibility of it being any sort of water parameter seems unlikely. We think it could be lack of oxygen, but that might just be because I’m used to freshwater tanks getting low at night due to plants. Sorry if it’s not much to go on.

I had a 100% fish kill in a 10 year mature tank that was loaded with fish and coral. During a nighttime power outage for a few hours all fish were killed but no damage to coral.

No parasite or disease will kill in 12 hours. Lack of oxygen or ammonia will kill quickly.

 

[austenreefer]

That h

Really hard without a picture of the tank. Normally fish will die in a tank at about three months due to ammonia poisoning. The fish and corals you added too soon for the bacterial population to catch up. This is very common at the 3 month mark.
Ammonia won't show up on a test kit after the fish die because the bacteria will process it pretty fast, just not fast enough to keep the fish alive.

A tank is not instantly cycled as soon as your test kits read there is no more nitrite. That just indicates that you have enough bacteria to take care of a dead shrimp or whatever you used to cycle the tank with.
It takes about 3 months for the bacteria to grow enough to add more than about one small fish.

What did the fish look like as soon as you found them? Did they have their mouths closed or wide open?

They "probably" did not die from parasites as you would have noticed that and fish "never" die from lack of oxygen unless the water was visibly cloudy.

I don't think going fallow is the answer. You need life in there to keep the bacteria multiplying and an empty tank will cause the bacteria you have to die back. The corals don't contribute enough ammonia to keep the cycle going.

I would add one small fish and nothing else for a few weeks. Then if all is well, add another small fish.

Good Luck

That sounds like the most likely answer. Thanks! We are gonna go with cheap fish like green chromes until we know the tank is okay again!