2 Week Tank Die off

[powerdyne6]

I had a previous thread up explaining some issues with my tank. Had some replies and opinions which was great. This will be a longer post regarding my timeline of what has happened and where I should go from here.

I started up my 75 Gallon Acylic Tank about 2.5 years ago. Sand Substrate some nice driftwood, plants, ,external filter and couple 200 watt heaters. Cycled with Dr. Tims ammonia.... took about 2 months.

I stocked it with 10 Penguin Tetras, 10 Blue Tetras (about 2 weeks later) and 10 Yoyo Loaches (about 1 month later)

Over the next couple years all was great... had a couple minor algae issues... was doing weekly water changes of about 50%.. using conditioner and also dosing some plant liquid fertilizer. Over this time frame I lost a few fish... couple jumped out (snuck through the cracks of my acrylic lids and a couple bloated up (seemed and looked like constipation and possible prolapse).

Lets fast forward to Dec. 18. 2025

At this point I had 8 Penguin Tetras, 7 Blue Tetras and 8 Yoyo Loaches. I decided to replace the fish I lost. I didn't find any Tetras to replace as I wanted to keep the same species. I looked around at a few more shops and found one wih a tank with 3 Yoyo Loaches. I only wanted 2 but didn't want to leave the last one alone, so I took the 3.

Dec. 20, 25

I added 10 Inpa Tetras from Aprils Aquarium. (I was back there this past weekend and their tank of these Tetras are alive and looking well) so most likely not the cause.

Dec. 21, 25

I added some more plants (particularily stem plants from a guy I had bought from in the past)

Dec. 22, 25

Added a bunch of floating plants.

Dec. 27, 25

I lost 9 Yoyo Loaches over these last 4 to 5 days. There were no external warning signs. They would all show similar characteristics before they died... kinda just floating around and drop to the bottom and then repeat.. They also weren't eating. Tested water and did a big water change while cleaning glass and substrate.. also cleaned the filter.

PH: 7.0
Ammonia: 0
Nitrite: 0
Nitrate: 10 to 20
GH: 2 Drops
KH: 2 Drops

Dec. 28, 25

A few of the tetras starting showing white spots on their scales. I assumed ich.. raised the temp to 85 did a few water changes, vacuumed the substrate and wiped down the tank.

Jan. 6, 26 to Jan. 8, 26

By this date I lost all Tetras.. most died during the nights so didn't really see and other issues except for the white spot.

Jan. 11, 26

I lost the last 3 Yoyo Loaches I purchased on Dec. 18.
At this point I have 0 fish left

I tested water

PH: 7.0
Ammonia: 0
Nitrite: 0
Nitrate: 10
GH and KH: 2 drops

At this point I have left my filters and heaters on. I do have some food in there to keep the cycle going and I also have some Dr. Tims I can add.

Where should I go from here? I have some Methylene Blue and Malachite Green. Should I do a cycle of one of these or both? Can I keep my cycle going by adding Ammonia to the tank? What temperature should I set the heaters to?
Do I need to strip the whole tank down and start from scratch?

All help would be appreciated

Thanks

 

[GaryE]

So, circumstantially, we can say a bacterial disease came in on the yoyo loaches. They were very vulnerable to whatever it was, but it spread out through the entire tank. 2 weeks is solidly in the quarantine zone. I use QT tanks, and the fish stay apart from the established ones for 4-6 weeks.

The only thing to do is restart. You can hope the epidemic has burned itself out after a couple of weeks. Almost every time I've bought something that brought in a nasty surprise, the QT tank has been safe after that time. Stripping it and disinfecting it will cost you all the plants, and may not be effective. There may no longer be a pathogen load surviving in the tank, as long as all the dead were removed and disposed of. Most of these internal bacterial diseases need fish to survive in dangerous numbers.

It's really an awful things when this happens.

One point (and others may have advice you see as better), do not restart with yoyo loaches, as they seemed vulnerable. If you are getting them again, give that time.

 

[Gertrudae]

I would run the tank without anything added for two months, then push it with food or ammonia and restock it with fish from other families when nitrite ist zero again.

 

[powerdyne6]

So, circumstantially, we can say a bacterial disease came in on the yoyo loaches. They were very vulnerable to whatever it was, but it spread out through the entire tank. 2 weeks is solidly in the quarantine zone. I use QT tanks, and the fish stay apart from the established ones for 4-6 weeks.

The only thing to do is restart. You can hope the epidemic has burned itself out after a couple of weeks. Almost every time I've bought something that brought in a nasty surprise, the QT tank has been safe after that time. Stripping it and disinfecting it will cost you all the plants, and may not be effective. There may no longer be a pathogen load surviving in the tank, as long as all the dead were removed and disposed of. Most of these internal bacterial diseases need fish to survive in dangerous numbers.

It's really an awful things when this happens.

One point (and others may have advice you see as better), do not restart with yoyo loaches, as they seemed vulnerable. If you are getting them again, give that time.

Thanks Gary

It sucks not knowing exactly what happened and I probably shouldn't of messed with things.

As for some of my last questions should I start doses of Dr. Tims and follow the directions? Should I even leave my heaters on? With them off my tank will sit around 70.

I was going to 1 last quick substrate clean as there is some food I need to get rid of as no one was eating)

 

[powerdyne6]

I would run the tank without anything added for two months, then push it with food or ammonia and restock it with fish from other families when nitrite ist zero again.

Thanks

So you are saying let it sit (keep filters on?) then after a couple months restart the cycle process again with ammonia doses?

 

[Gertrudae]

Filters - keep it going
Heater - not necessary

The cycle process won't stop completly, it will only need a little push for the new workload before the new fish arrive.

 

[Gertrudae]

Maybe you'll need fertilizer, keep an eye on your plants.

 

[FranciscoB]

Sorry for the losses and frustration. Hopefully restarting will be successful.
Actually, you do know what happened. You introduced fish and plants, either of which brought pathogens that wiped out your established tank. Quarantine is a must. Although not everybody does it, it is just not worth the risk.
The advise of running the tank empty, orrhaps with just plants for a couple of weeks is sound advice
Good luck!