Fish Dying Overnight.

[Brooke B]

I need serious help. 

I’m fairly new to fishkeeping, about 8 months in. I’m having an issue with one of my tanks and I just have no clue what it is or how to deal with it. 

I had something wipe out my entire shoal of pea puffers overnight. They were to totally fine, eating normally the night before and by the middle of the next day they were all gone. No symptoms except one had a small fuzzy patch on his head that had appeared that morning, the others had nothing. Someone had brought up columnaris being a possibility. 

I cleaned out the tank, got new sand, boiled my driftwood, did a hydrogen peroxide dip on my plants, scrubbed the tank itself and rinsed with aquarium salt. The only thing I didn’t touch was my sponge filter, in hopes of keeping some beneficial bacteria. Maybe that was my mistake. 

I refilled the tank and dosed with aquarium salt according to the package. 

I decided to try to use the tank as a breeding tank for Amy pair of German rams that are currently in my other community tank, but didn’t want to risk anything so I moved a few mollies over that tank since I have a bunch from breeding. 

Everything seemed to be going well for a few days, but then the same thing happened. Last night fine, this morning, gone. 

What do I need to do to make this tank safe again? Where did I go wrong? Should I cometlety sanitize everything, filter included, and recycle the tank? This was my first tank that I’ve put ton of work into, and I don’t want to have to lose all of my live plants and everything.  

Also, water parameters never left normal ranges,  ph 7.8, ammonia 0, nitrites 0, nitrates 10, temperature kept at 80 degrees. My other tanks are fine, so no issue with my tap water.

[JE47]

Maybe @Colu can help you

[Colu]

On 9/14/2023 at 6:11 PM, Brooke B said:

I need serious help. 

I’m fairly new to fishkeeping, about 8 months in. I’m having an issue with one of my tanks and I just have no clue what it is or how to deal with it. 

I had something wipe out my entire shoal of pea puffers overnight. They were to totally fine, eating normally the night before and by the middle of the next day they were all gone. No symptoms except one had a small fuzzy patch on his head that had appeared that morning, the others had nothing. Someone had brought up columnaris being a possibility. 

I cleaned out the tank, got new sand, boiled my driftwood, did a hydrogen peroxide dip on my plants, scrubbed the tank itself and rinsed with aquarium salt. The only thing I didn’t touch was my sponge filter, in hopes of keeping some beneficial bacteria. Maybe that was my mistake. 

I refilled the tank and dosed with aquarium salt according to the package. 

I decided to try to use the tank as a breeding tank for Amy pair of German rams that are currently in my other community tank, but didn’t want to risk anything so I moved a few mollies over that tank since I have a bunch from breeding. 

Everything seemed to be going well for a few days, but then the same thing happened. Last night fine, this morning, gone. 

What do I need to do to make this tank safe again? Where did I go wrong? Should I cometlety sanitize everything, filter included, and recycle the tank? This was my first tank that I’ve put ton of work into, and I don’t want to have to lose all of my live plants and everything.  

Also, water parameters never left normal ranges,  ph 7.8, ammonia 0, nitrites 0, nitrates 10, temperature kept at 80 degrees. My other tanks are fine, so no issue with my tap water.

With mast mortality I would be concerned about cleaning products or air freshener getting into tank at certain times of the year water company will flush there pipe with higher doses of chlorine chloramines  did you  do a water change the day before they died and did you add a water dechlorinator like prime @Brooke B

Edited September 18, 2023 by Colu