Bacterial infection in tank?

[Ajw52508]

Hi everyone, once again I'm turning to these forums for advice. I have a 20 gallon tank that was established this past October. The tank housed 7 Glofish, 2 Cory catfish and 2 Amano shrimp happily, the only fish I lost was one of the Cory's, which died about a week after I bought it, and I think it was sick from the beginning.

The problem started when I added 2 Black Molly's about a month ago. One of the Molly's never really seemed to adapt (appeared slow, hid often) and died about a week ago. Today I lost the other Cory. While doing my weekly 25% water change tonight, I saw that the other Black Molly had a long white stringy feces hanging from her underside. She otherwise eats well and appears healthy, but my concern is that there may be some kind of infection or other problem in the tank which has caused the other fish to die. If there is a problem should I treat the whole tank or isolate the Molly? Any help here would be greatly appreciated, my daughter's will be very upset if we lose all of the other fish! Thanks!

 

[Demeter32]

I would start by looking into the water parameters. If you can, please test the water for nitrites, nitrates, ammonia, etc.

Long white stringy poo is associated with internal parasites and it sounds like you caught it in time for the other black molly, seeing as how it's still eating. API general cure or Tetra Parasite Guard should hopefully clear that up. Treat the whole tank for internal parasites. But you might have to temporarily remove the shrimp, I can't remember if either med is invert friendly.
Part of the reason that the corries dies off could be that they were stressed. They really need to be with several others of their own species or they don't do so well.

As a side note, you stocking seems a little iffy. In a 20 gallon (is it a long or a tall?) I'd only have the school of glofish (zebras or white skirts?) and then the school of corydoras. In my personal opinion, mollies should be in a 29gal. They are social fish, like corys, and they like their swimming room. Having an suitable number of mollies in a 20 gallon is probably going to be too much of a bio load + little swimming room.

 

[Ajw52508]

Thank you for your helpful reply. I did test the water using the strips and the nitrates were in an acceptable range, with no ammonia or nitrites. I know that the strips aren't the most reliable but it's what I've got for now.

The tank is a 20 gal tall, hoping to upgrade sometime this year. I didn't realize that the Cory's needed a school, and I also thought the 20 gal was big enough for a couple of Molly's. Live and learn I guess, hopefully the parasite will clear up. Thanks again!

 

[Ajw52508]

I began the API general cure treatment today, before starting the treatment I removed the Amano shrimp and will be keeping them in a separate tank. The directions said to treat the tank, 48 hours later give it a second treatment, and 48 hours thereafter to perform a 25% water change. Can you advise on when it would be safe to return the shrimp to the tank? Thank you.

 

[Demeter32]

A couple days after the 25% water change. I hope you removed the carbon from the filter before starting the treatments, if not then do it asap. After the treatment is complete you can add the carbon back in. It will absorb the rest of the meds making it safe to return the shrimp.