Are My Past Pets Killing My Fish?

[EmCeeG]

I have a fish-tank that was not always a fish tank. I used to be a lizard tank, then housed land hermit crabs. It includes mollies and a rainbow shark, and they seem to thrive. Yet, whenever I put angelfish in it, they end up dying. I thought it was just bad luck, or sickness from the store (The neighborhood Petco, where Ive seen a dead fish in a tank, and find it still there in 2 days.) But one of my few fish-keeping freinds told me the tank's prior usage could be whats dooming my fish. Is this true?

 

[waterdrop]

Hi EmCeeG and Welcome to TFF!

I don't know the answer to your question but I'm sure some of our other members may have experience to share. A few questions I'm sure many of them may have is how long the tank has been set up for fish? When were the mollies and rainbow shark put in? What is the tank volume?

How did you go about "cycling" the tank (assuming you are aware of the term "cycling", otherwise we can help with that.) Do you know whether your local water tends to be hard or soft?

One issue that comes to mind is that mollies tend to need very high mineral content, whereas angels are south american fish that like very soft (low mineral content), acid water. These considerations would be very secondary to any issues of the tank not being "cycled," but they could be important.

~~waterdrop~~