Tropical fish dying quickly after move wha

[Inkweaver313]

Help! Backstory:

I had a 45 gallon tank with mollies and neon tetras set up for about a year. The mollies were breeding like crazy (as they do) so I rehomed all but 5 males. I needed the 45 for a rescue goldfish I got so I purchased a 30 gallon tank.

I set it up, let the temperature settle to 75 degrees Fahrenheit. I tested the PH and it was in the normal range for my tank (around 7). I added cycled media from the 45 to the tank and acclimated them a couple days later.

Overnight all of my neons died. Now my mollies are laying on the bottom of the tank gasping. There’s obviously no ammonia or anything in the tank as the water is brand new. I see no spots or signs of ich. I have no idea what it could be and I’m trying desperately to save the mollies.

I’m currently treating with aquarium salt but I have no idea what could be going on? Any advice would be appreciated.

 

[Colin_T]

The fish are being poisoned by something in the new tank.

Did you use declorinated water?
Did you use fish only buckets?
Did you wash the tank out with anything?

Your best bet is to do a 75% water change every day for the next week. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Add some carbon to the filter and replace it in a couple of days.

Increase aeration/ surface turbulence.

 

[Inkweaver313]

I woke up to another death. I lost one of the 5 mollies. I’m at such a loss for what this could be. There’s no fraying of the fins. There’s no white dots. There’s no fuzzy or discolored patches on them. Their coloring is normal. But they’re not eating, they’re all sitting at the bottom of the tank just shimmering and gasping.

I have 6 aquariums and all the materials I use for them are fish only stuff. I have separate buckets and siphons for my goldfish tanks, tropical tanks, and saltwater tanks.

I rinsed the tank with warm water before setting it up, used new gravel that I rinsed until the water ran clear, and decorations that I cleaned with warm water we’re brought over from their old tank. They have two air stones (one on each side of the tank). I’m so lost.

All of the water has been dechlorinated.

Their filter has carbon, but I did add a little more. Like you suggested I did a 75% water change this morning. I also slightly raised the temperature and added aquarium salt again. Anything else I could do? Any idea what this could be?

 

[Colin_T]

move them into a different tank and see if they recover

 

[Byron]

There’s obviously no ammonia or anything in the tank as the water is brand new.

Agree with Colin, but can you explain this sentence? Did you test for ammonia, nitrite and nitrate, and if so, what were/are the numbers?

Just from what you've posted, I would suspect ammonia poisoning, but the above info may tell us.

 

[Inkweaver313]

Ammonia is 0, nitrite is 0, nitrate is 0. I just put them in this tank and then did a huge water change.

 

[Inkweaver313]

Update: no new deaths but the remaining mollies don’t look good.

I’ve moved them to a new tank and there’s been no change. I’ve been treating with LifeGuard broad spectrum because I have no idea what this is. I’ve also been doing water changes and adding salt and upped the temperature in the tank.

Yesterday two of the mollies were swimming around and they were eating. I got my hopes up. Today nobody will even take a nibble and they’re all laying on the gravel again.

 

[Jimdude]

I had a similar experience once. I bought a new tank from a big box store $1 per gallon sale. I used sand and a sponge filter from and existing tank. I lost all but 1 fish quickly. Even though I rinsed the tank out, I later found some funky white stuff floating at the surface. I told the manager of the store that I felt the tank was contaminated with something and he exchanged it. New tank was good.