Fish dying fast, Ammonia, Nitrates, Nitrites at zero

[stalinman1]

I have a 29 gallon that crashed a couple of months ago. I had a surviving bristlenose pleco and a cherry shrimp. Since then my tank has remained cycled. I got the tank back up to par and added 3 neon tetras and 2 glowlight tetra two months ago. One glowlight died, I'm assuming it had issues when I purchased it. In any case I waited a couple of weeks to add more fish. One week ago I purchased two peacock gobies, two neon tetras, two cherry shrimp, and an assassin snail. Normally I wouldn't add so many fish at once, but have added several new plants at the same time and water parameters have remained unchanged.
Two days after the purchase I lost a neon, the next day I lost another neon, etc. Yesterday two fish died and today two more. All in all I lost my BN pleco whom I've had for several months, 1 cherry shrimp, my glowlight tetra, and 5 neon tetras within this one week. I am baffled and have no idea what's going on. My only theory is that the gobies could be killing them, although I haven't seen them attack at all. I tested my water levels yesterday with my API kit and Ammonia, Nitrates, and Nitrites are all at 0. The fish haven't looked sick at all, I just find them dead. I've never lost fish like this before, other than my tank crashing due to my own negligence in the past and I'm frustrated and not sure what the problem could be and don't know if I should take the gobies back or not. They are a male/female pair but I haven't seen them act aggressive at all. The only thing I've done differently is add an appropriate dosing of seachem flourish a week ago with a 20% partial water change, which I have always done. I wondered if it was the flourish but thought if it was I would have lost all of the shrimp and they would have gone first. Any advice would help.
Also, the temp is at 78, I have a marineland bio wheel 200 rated for 50 gallons, and currently left are my two peacock gobies, an assasin snail, a mystery snail, and two cherry shrimp. PH tested at 8.6. I know it's high but successfully acclimated a GBR and Angel and they thrived before my tank crashed, not to mention I've had the first few tetras for quite a while before the new additions when everything started dying off.
Fish get fed shrimp pellets on occasion, usually they get high quality angel food flakes.

 

[irdajoh]

Tap or well water, should call the city to see if they've changed the chemical treatments. Do you quarantine new stock at all? Did the fish show any sign of deseases? Ph is high for sure and that could be a cause. Driftwood helps the pH if you want to lower it. If tap water do you condition the correct amount? Air stones working correctly? If I'm not mistaken tetra are very sensitive fish, something has to be off with the water. How long has the tank been set up?

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[uncgirl1]

I had a similar experience. My tank was well established and all water parameters were great. As in 0/0/10. Healthy and happy fish. Then I bought new cory catfish. One by one, fish started dying. I was traumatized and looked everywhere for answers. Tap water was the same. There were no signs of illness on any fish. Then about 2 weeks later, I still had a few fish, I noticed a rummynose tetra with a white band. More fish started dying. Long story short, it was a parasite. Took over a month for it to kill everything but it wiped out my entire tank. I think I also had columnaris (sp?). I learned that once one thing happens, it happens quickly and is often times muddled with other illness as well. I figured it out to late and was not able to save anything.

I learned a lot from that and am now rebuilding. I now have a QT tank and well as Paraguard on hand in case of emergency.

I'm sorry you are having to go through this and hopefully it's not a similar experience to mine.

 

[J.Mcpeak]

See the pH/Kh co2 triangle.

That's my guess. (High stock levels of plants and fish)

Co2 being used by plants and fish (high pH is a good indicator) during photoperiod on.
Test pH before lights come on first thing in the morning, if it is significantly lower (acidic) than the tested result 8.6 then that is the issue.

Co2 builds up overnight lowering pH, then it's used during the day raising pH.

(Spend a day testing hourly to see the rise, if the daily shift is too great, that's the problem)

I've just lost two Cory from this exact problem. Temporarily I've reduced the photoperiod. It's been a few days, no further losses.

 

[irdajoh]

See the pH/Kh co2 triangle.

That's my guess. (High stock levels of plants and fish)

Co2 being used by plants and fish (high pH is a good indicator) during photoperiod on.
Test pH before lights come on first thing in the morning, if it is significantly lower (acidic) than the tested result 8.6 then that is the issue.

Co2 builds up overnight lowering pH, then it's used during the day raising pH.

(Spend a day testing hourly to see the rise, if the daily shift is too great, that's the problem)

I've just lost two Cory from this exact problem. Temporarily I've reduced the photoperiod. It's been a few days, no further losses.

Hey... I like your theory on what's going on here. Now could this cause fish to get stressed and get bacterial infections? I have 1 single mollie in my tank out of 8 who's been having bacterial problems... my parameters during light is normal 7.8pH, 0 ammoins, 0 nitrites, nitrates 10-40. I have just the weirdest feeling this one fish dislikes the chemistry of my tank.. he's in my qt tank being treated for it all but gosh if I put him back in and he gets sick god knows what I can do to help him.

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[J.Mcpeak]

That's no theory! That's basic water science.

Now for mollies, I am led to believe they prefer brackish water, but I've not kept any.
The jury is out on this because there are so many yes/no answers. I'm sure live bearers prefer harder water. It's safe to say light brackish will present no problems for these, they can be kept in a full marine environment if acclimated properly.

PH swings like this can most certainly kill a fish so it seems likely they can cause other stress related issues. Bacterial infection is on the list.
Test your hardness, GH. Make sure it is suitable, adjust slowly. Test both source water and tank water. They should be near enough the same.
I hope this helps!

 

[irdajoh]

That's no theory! That's basic water science.

Now for mollies, I am led to believe they prefer brackish water, but I've not kept any.
The jury is out on this because there are so many yes/no answers. I'm sure live bearers prefer harder water. It's safe to say light brackish will present no problems for these, they can be kept in a full marine environment if acclimated properly.

PH swings like this can most certainly kill a fish so it seems likely they can cause other stress related issues. Bacterial infection is on the list.
Test your hardness, GH. Make sure it is suitable, adjust slowly. Test both source water and tank water. They should be near enough the same.
I hope this helps!

API master kit dosent have GH right, and I hardly see the kits at petsmart but I'll check again today for sure.

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[J.Mcpeak]

API master kit dosent have GH right, and I hardly see the kits at petsmart but I'll check again today for sure.

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They do sell a GH/Kh kit they must sell single sets for each? Maybe they don't stock it.
Other brands are available and they all work on the same principle.

Yes, you are correct. The master kit doesn't have this parameter.
I use the API master and jbl for GH/Kh and wide range pH. Maybe they have those?

I'm an English so I'm not familiar with U.S. stores, maybe somebody from your neck of the woods can help?
If all else fails, Amazon!

 

[irdajoh]

Amazon may be my best bet here. It seems like they don't stock them at the stores but I'm at work so I can't tell just yet DX. I'll check online

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[J.Mcpeak]

I'd do that, you'll get it in a day or so. Job done!
(Saves a lot of legwork too!)
Or maybe phone and check with the local, they may just ship one in for you? Most places would do this, but you wait for the delivery.

 

[irdajoh]

It's coming on tomorrow! I fear it may be what's causing the problem

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