What happened to my tank?

[32147]

Here is the background, my 75G fresh water planted tank crashed and EVERYTHING died about 5 days ago. I would really like to know what happened so if you have any ideas or suggestions please send them.

To answer the most likely questions...

Water Parameters: Results from a friend.
“NH3-0, NO2-0, NO3-5, KH-3, GH-3, pH-7.4, Cu- 0 all excellent results signs of optimal aquarium water. Then tested PO4-off the chart... my kit reads to 10ppm soon as I added the regents it turned dark. You’re supposed to wait 3 mins. to read it and wait for full colour. This would be suspected from an overdose of ferts though. I have an Fe kit maybe I'll test that but it takes 30-45 mins. When I have been fertilizing with Tom Barr EI method which is heavy doses of PO4 most I had was 1.5ppm. Is this the problem? I don't know?”

Size and Inhabitants: 75G with three Tetraodon Abei, 30 or so Harlequin Rasborae, some Cardinal Tetras, some Glowlight Tetras and a Siamese Algae Eater. As well as a nice selection of plants, some Malaysian Trumpet Snails and whatever Marbled Crayfish have so far avoided the Puffers.

Feeding: Feed twice a day most days, flake food for the Tetras and Rasborae, Marbled Crayfish and Frozen Bloodworms for the puffers.

Water changes: OK, I admit it I am not remotely as regular as I should be but usually each tank gets 30-50% change once every week or two.
In this particular case there was one 60% the day before the crash (day zero) and two changes since then, one at 100% and a second at 50%. NOTE after these three water changes I added an Ultra Violet Sterilizer then added 6 Rummy Nosed Tetras which were dead within 24hrs.

Substrate: two beds of Eco-Complete and a bed of gravel in between them.

Products used: Seachen Flourish which was added the night of the first crash. At first I thought that might be the problem as I dosed about 4 or 5 capfuls in a 75G tank and the recommended is one cap for 60G. Prime water conditioner used in all my tanks from the same bottle.

Filtration: one Magnum 350 Pro with Bio-Wheel, one Rena XP3, and one Penguin 660-R sponge filter with a power head attached. Also on day four I added a 24W in tank UV sterilizer
The tank has been up and running for two or three months. I cycled it using some seeded HOB filters moved from other tanks in the apartment.


The sequence of events.

DAY ZERO
Water change (60% or so) and addition of fertilizers. I poured more Seachem Flourish in the tank than I had intended, perhaps 5 capfuls. The recommended dosage according to the label is one capful for 60G once or twice a week. I use a capful or two every three weeks or so. All is fine at 2200hrs on day zero. No cause for concern all is, and has been, well for about two or three months.

DAY ONE
10:00hrs day one ALL the fish are dead without exception, and lying on the bottom. The Abeis are dark and slightly bloated, the other fish are pale but not noticeably bloated. I remove all the dead fish and clean out the overflows of dead fish as well. I take a water sample to give to a friend with test kits. The water is distinctly yellow and smells bad. I start to try to figure out what happened. All other tanks in the apartment are fine although they were not maintained on day zero. I do a 100% water change....well really about 95% as I don't ENTIRELY empty the tank, there is still a couple of inches of wet substrate.

DAY TWO
The plants are melting and losing colour. I remove about 60% of the plants and all the driftwood. Sorry I am not good with plant names but one of the "red" ones is almost white now and many of the green ones are also washed out and pale. This causes me to suspect the fertilizers. The water looks a lot clearer and no longer smells.

DAY THREE
More of the plants are dying; the Java Ferns are all bronze/brown and look shrunken. I remove more plants. Now there are about 15% of the original plants left and they don't look great but I really don't want to lose them all. I am hoping they will regenerate or bounce back. I do a 50% water change.

DAY FOUR
I borrow an Ultra Violet Sterilizer and add 6 Rummy Nosed Tetras. All is well at 22:00 hrs

DAY FIVE
The Tetras added 12-14 hours ago are dead and on the bottom of the tank. Their noses are still red and they don’t appear pale or bloated.

Hypotheses/Suggested Causes

So the mystery remains...what went wrong? Since I have done over 100% water change between the first deaths and these Rummy Nose deaths, there is NO WAY that a slight overdose of fertilizers is the cause. I only added 4 or 5 capfuls of Seachem Flourish which is at MOST 4 times the "recommended dose". After these water changes the fertilizers would be so dilute that they would be of negligible effect and should not have affected the Tetras last night

Here are some hypotheses/suggestions from forum members along with my answers.

Somehow, one of the Abei puffers died AND had stored-away toxins in him/her. Then, one of two things happened:
1) The toxin was released and killed all of the fish.
2) The toxin was released into the dead puffer's flesh, and all of the fish ate parts of the Abei (which fish often do), which resulted in their demise.

This is a possibility but there were more deaths after the Puffers were removed and the water was changed.


What fertilizers do you use? Do you use it in your other tanks or aren't they planted?
Seachem Flourish and I use it in all my tanks. All from the same bottle.

Are the heaters working or shorting out? Is there any condensation inside the heater, any hairline cracks?
Temperature is steady at 75. No electrical shorts or condensation can be found.

It’s possible that the switch in the heater failed and there was a temperature spike?
Not likely, the temperature reads fine and the two sets of fish death were days apart.

Maybe something was sprayed into the air (perfume, cleaning agent, etc.)
Nothing that I know of was introduced to the atmosphere and the other tank in the same room suffered no ill effects.

Perhaps something horribly poisonous from the ceiling fell into the tank?
Not likely as the tank has glass covers.

What do you have for substrate in there? Could have been a gas bubble?
Eco-Complete and some gravel from another tank. Gas bubble twice in 5 days is not likely.

Anything new added to the tank in the last 72 hours. Food, Salt, Ferts/Medicines/Treatments, Rocks, Plants, Ornaments/Shells, Fish?
Nothing new was added

Faulty CO2 injection?
No CO2 in this tank

Is there a film on the tank's surface?
No

Does the tank smell funny?
Yes…kind of like dead fish

Any kids been around the tank (unsupervised)?
No

Using anything different on your hands degreasers/hand creams?
No

I'm not sure if scented candle can harm fish, I know they can drop a bird in their tracks
No scented candles or incense or air fresheners, etc.

Did anything look wrong with the fish?
Some pale and some bloated

Had any of them been eaten by the others (indicates if they all died at once)?
No evidence of cannibalism.

Did you find them all?
Yes

The question might seem out of place... Do you have a cat?
No cat or dog or other pets…no girlfriend or recent ex-girlfriend either if that is your next question.

Is it possible that the Prime I use in water changes could affect this one tank and not the others I have?
No

Is it something in my tap water or the buckets I use?
Same answer... No it would affect all the tanks not just the one.

So could it be that my hands became contaminated on Monday night with something that then got transferred only to that one tank? I had been out “Urban Mining” (garbage picking)
Possible but not likely. I have difficulty believing that I would not have noticed something as potent as this would need to be to cause this amount of damage even after more than 100% water change.

Did one of the first batch of fish die and somehow transfer toxins to the others somehow (perhaps they all ate a bit and died)?
Not possible because the Rummy Nose I put in on day 4 had no contact with that first batch of dead fish.

Conclusions

It must have been some kind of poison that is strong enough that residual toxins still in the substrate or filter can kill after UV sterilization, 150% water change, four days from onset until now and removal of ALL the fish, ALL the driftwood and MOST of the plants.


Next Steps

Currently the tank is still running with the filters and UV sterilization because I don't know what else to do. I am at a loss. I guess that I will tear it down sometime this week and clean what I can and throw out the rest.


Here are a couple of links discussing the situation as it was occurring.
viewtopic.php?f=4&t=14070

Here is the thread in my local club where I discuss the crash.
http://ovas.ca/index.php?topic=30109.0

[Nick]

Was this by any chance the bottom of the bottle of ferts, the "last of it"? And if so, was this the last tank where you finished off the bottle? Ferts can settle if they get old, and if you don't shake them well with each use, certain substances will build up in the bottom. Most aren't supposed to settle, but the homogenizing agents can degrade with time.
Also, eco-complete is a porous substrate, meaning a surplus of dense settled ferts could sink to the bottom, then absorb into it, and be slowly released.