My guppies and mollies keep dying

[GNAAAR]

So I got a fish tank from my brother that he used to keep frogs in because I bought a Molly that ended up being pregnant and it gave birth and I really wanted to start breeding those as well as guppies which I have successfully bred for about 2 years. I scrubbed all calcium deposits and dried algae out of the tank but the fish are dying. Every one would die and have closed fins (sometimes becoming a point at the end) and a greyish white or blue slim covering their body. Today I ended up finding some white stuff in the inside and some on the outside of the black piece at the end of he heater. Would that by any chance be the problem.

The heater came with these white spots, should I scrape them off?

 

[NRB]

Hi GNAAAR,

I don't think it is the stuff on your equipment, unless it is some kind of chemical. Guppies and mollies don't do very well with sudden changes in water parameters.

To start with is your tank cycled? If not that could be the issue.

I would purchase the API master test kit, this will help with cycling, but you can also check your aquarium ph. Make sure your aquarium ph matches that of the guppies natural ph range. Also, you may want to test the water of the fish store when you buy more guppies. If it is way off from your water that could be the problem.

Look up drip acclimation, that is the best way to introduce fish to your tank.

Best of luck!

 

[GNAAAR]

I set up this tank the same way I always do with my tanks and it always works fine but it's just something about this one that has me troubled.

I have done some research and I found mixes of answers such as parisites, bacteria, ph etc. So I went with a full bleach clean, vinegar to scrape all lime out and a full water change plus I took those things that hold benificiql bacteria that was in another tank to it

Do you think I will continue having problems?

 

[NRB]

That sounds like a plan, just make sure to rinse everything very well and air dry if possible. Bleach should kill everything, so you can at least eliminate parasites as a problem.

Is there any other decorations or driftwood in the water? If driftwood is not approved for aquariums, it can sometimes have chemicals on it that could be killing your fish.

 

[GNAAAR]

I rinsed out the tank about 4 times and there is no driftwood, just decorations I've used previously and I know are safe