Massive overnight die off in African Cichlid tank

[Naughts]

could you have some stray voltage from a heater, light, or filter motor, wave maker, or similar... it seems pretty traumatic to lose that many fish overnight, however, yes, ammonia could kill that fast...

I've heard of that happening with stray voltage but could there be survivors?

 

[Magnum Man]

it's a big tank ( 125 gallon ) maybe if the live ones were on the opposite end from the voltage leak... I'd check all the electrical appliances, to make sure all are working, & that none gives shocks... if something is not working, it may have shorted out through the tank???

 

[vince82]

Does the heater work? Is temperature stable? A heater with faulty temp sensor could have spiked the temperature up during the night?

 

[BobbyZee]

Nope. The filter bacteria live in the aquarium water, which has a certain chemistry (GH, KH & pH), temperature, and is free of chlorine/ chloramine. Tap water can be different to these and everything that is different can affect the bacteria. Your water company might have done work on the pipes recently and added extra chlorine/ chloramine to make sure nothing lives in the water and you could use that heavily chlorinated water on the filter and kill the bacteria. Major temperature changes can affect the bacteria. If the filter media is exposed to sunlight (even for a few minutes), it can affect the bacteria.

Thank you, Colin, I do things that way from now on.

 

[BobbyZee]

Does the heater work? Is temperature stable? A heater with faulty temp sensor could have spiked the temperature up during the night?

Heater good, temp. stable. Nighttime spike extremely unlikely.
In tanks of this size one does not generally see rapid rises and drops in temperature. The tank has two heaters, one at each end. I did recently hear of a person with Altums who lost his group when the single heater malfunctioned and the water hit 100. The site administrator and extremely well-known, experienced breeder said that if he had used two heaters instead of one, he would not have lost his fish. I have always used two in the big tanks, but thought it was because if one went out completely, the water would still have some heat. I never even considered the possibility of a single heater malfunction causing the water to hit 100 and killing all the fish.

 

[vince82]

Heater good, temp. stable. Nighttime spike extremely unlikely.
In tanks of this size one does not generally see rapid rises and drops in temperature. The tank has two heaters, one at each end. I did recently hear of a person with Altums who lost his group when the single heater malfunctioned and the water hit 100. The site administrator and extremely well-known, experienced breeder said that if he had used two heaters instead of one, he would not have lost his fish. I have always used two in the big tanks, but thought it was because if one went out completely, the water would still have some heat. I never even considered the possibility of a single heater malfunction causing the water to hit 100 and killing all the fish.

Yeah if you have a single heater it's more likely.
I had a heater fail before and I caught it before any death, but I still use a single heater inline to the canister and this frequently worries me.
However I am afraid that with 2 heaters one breaks, you never notice because the other works double and keeps up, then the extra work breaks heater 2 and you are back to no heater.... Soooooo pretty much the same IMHO.

 

[Magnum Man]

I use the new heaters with digital read outs... if they were on opposite ends of a large tank, like the OP's you would notice a couple degrees difference in the temperature read outs... I put my controllers where I see them, when doing tank chores...

 

[BobbyZee]

I use the new heaters with digital read outs... if they were on opposite ends of a large tank, like the OP's you would notice a couple degrees difference in the temperature read outs... I put my controllers where I see them, when doing tank chores...

My hands have become so sensitive that I can stick my finger in & tell the temp within a few degrees. lol.

 

[BobbyZee]

it's a big tank ( 125 gallon ) maybe if the live ones were on the opposite end from the voltage leak... I'd check all the electrical appliances, to make sure all are working, & that none gives shocks... if something is not working, it may have shorted out through the tank???

I really don’t know. I’ll have to ask my boyfriend. He’s a genius who knows everything. lol. lol

 

[Wills]

I've read most of the post and definitely sounds tough!

I just wanted to add in that I've heard of cichlid tanks reaching a critical mass in terms of oxygen in a tank, so they just gradually grow and grow and eventually there is not enough oxygen circulating in the tank and you then lose one and that starts the ammonia spike. Its just anecdotal but thought worth mentioning.

Wills

 

[BobbyZee]

Wills, that is my latest theory. Inadequate oxygenation and the annual addition of a few fry that escaped predation. It was my most densely populated tank. There were numerous large hides & a death inside may have very well eluded me. I thought of shifting some to other large cichlid tanks, but I’ve observed they set up rigid social hierarchies, so I let them be. Big mistake.

 

[FishyD]

My hands have become so sensitive that I can stick my finger in & tell the temp within a few degrees. lol.

It's pretty crazy but yeah. 75 feels cool to me. 72 is coldish, and 80 is on fire hot to my hands. We know in an instant if we should have a look at the thermometer.

 

[BobbyZee]

I’m being told that fish who die from oxygen deprivation have flared gills.
I was in too much shock to really notice while quickly removing them.
Would the gills have been so grossly flared as to be impossible to miss?

 

[BobbyZee]

Already mentioned, but if you are certain a toxin like an aerosol could not have entered, then a fish dying unnoticed seems like the next best guess. I am pretty sure a chlorine problem would have shown some noticeable symptoms day one, as it is obviously a strong toxin.

Could have been that and O2 deprivation.

 

[Ceez]

You must be gutted, sorry this happened. Agree with Colin, clean your filters in removed tank water. I always remove about 3.5-4 gallons in a 5 gallon bucket of my tank water when I'm doing a water change to clean filters with.

Also a heater controller is a good idea especially with a tank full of fish that cost a decent amount of money. If the heater gets stuck on the controller will shut it off once it reaches the temp you set it at so you don't fry your fish.

I also agree that your ammonia level was more than likely caused by the amount of dead fish you had. I really wonder why you had a die off though, something we could all learn from I'm sure