Searching for an answer why my Tetras died

[Sue Weatherwax]

Hello,
I just signed up today in hopes of someone who might be able to answer my question.

I have had a 10 gallon aquarium in my office at work ever since Dec. 2015. I only use RO water. Change the water once a month by taking out at least 4 gallons. Every other month I vacuum the gravel and put in a new filter. I started with a hardy fish - 8 Tetras, since this was a new tank and that is what the fish store told me I should get. Along with the tetras I also got a catfish.

They were all doing great until about a month ago. My catfish would turn white in some places, but then after a few days it looked like it cleared up. One by one the Tetras started to die. They would lay down on their sides on top of the gravel and eventually die.

I told the aquarium store what had happened and I brought in one of the fish along with a water sample from my tank. They could not find anything wrong. Infact, they said the water sample was perfect. No signs of parasites on the fish, etc under the microscope.

The only thing I have done differently is I added a thermometer probe (which has metal on the end) and submersed it in the tank. I even asked the store if the metal could have been poisoning them slowly over time, but they said no.

Has anybody experienced anything like this? Anything you can share will be much appreciated.

Thank you,
Sue

 

[Delapool]

Hello,
I just signed up today in hopes of someone who might be able to answer my question.

I have had a 10 gallon aquarium in my office at work ever since Dec. 2015. I only use RO water. Change the water once a month by taking out at least 4 gallons. Every other month I vacuum the gravel and put in a new filter. I started with a hardy fish - 8 Tetras, since this was a new tank and that is what the fish store told me I should get. Along with the tetras I also got a catfish.

They were all doing great until about a month ago. My catfish would turn white in some places, but then after a few days it looked like it cleared up. One by one the Tetras started to die. They would lay down on their sides on top of the gravel and eventually die.

I told the aquarium store what had happened and I brought in one of the fish along with a water sample from my tank. They could not find anything wrong. Infact, they said the water sample was perfect. No signs of parasites on the fish, etc under the microscope.

The only thing I have done differently is I added a thermometer probe (which has metal on the end) and submersed it in the tank. I even asked the store if the metal could have been poisoning them slowly over time, but they said no.

Has anybody experienced anything like this? Anything you can share will be much appreciated.

Thank you,
Sue

Hello, the use of only RO water might be a long-term problem as it won't contain much in the way of minor salts for the fish. Better to mix a blend of RO and tap - assuming there are no issues with the tap water?

The catfish is probably too large unfortunately for the tank (now or later). The white could be fungal or bacterial. As it spread to the other fish I would suspect bacterial.

However I'd suggest getting a water test kit like the API freshwater master test kit as you should check water chemistry first just in case.

 

[Megg]

I would suggest 30-40% water changes weekly. Siphon the gravel while you're removing the water. Only change your filter pads if they're falling apart. Most of your beneficial bacteria live in these, so when you throw them away you're throwing away your cycle. If the pads are dirty you can swish them in a bucket of aquarium water (right after a water change, you can use your bucket of dirty water) and this should clean them.
*What kind of tetras and catfish?
*Did the store test your water with strips or liquid?

Sorry for all the questions, but they'll definitely help.

Depending on the tetra it sounds like you're a bit overstocked... Unfortunately if the catfish is a Cory, they need to be in shoals of 6 or more and you don't have room in your tank. Any other kind of catfish will be too large.