Zebra Danio With White Lump

[Promisedsin]

The danio with the lump has died but I would still like to find out what was wrong in case I did not get it out soon enough and my remaining danios start showing similar symptoms. I had posted on a different forum with no luck.

I came home to one of my danios missing its tail which I assumed to be from the larger of the danios nipping fins and I noticed that one had a white lump at the base of his tail.

He was very lethargic and remained at the surface of the water. The readings of my tank were as follows:
Nitrate: 10ppm
Nitrite: .1ppm
Ammonia: 0ppm
Hardness: 100ppm
Alkalinity: 120ppm
pH: 7.6

He was dead when I woke up the next morning. The tail on the other danio is growing back so I don't think they will get sick but I want to know what im dealing with if it shows up again. Thank you

 

[dkpate]

You should have 0 nitrite in your tank, and should be doing water changes to get that down. Not sure about the spot, as I have never seen anything like that, but could it have been a tumor? Did it grow?

 

[Promisedsin]

I am doing water changes to get it down. And I do not believe that it growed. It appeared over night and then he was dead the next day. It didn't look any bigger when I found him.

 

[happygirl65]

It was most likely a result of ammonia burns and then nitrite poisoning. It could have been a fungus or an opportunistic infection that grabbed hold while the fish was in a weakend condition. With fish that are used to cycle a tank, often it will start with an ammonia burn that the fish can sometimes live through but in another week or two when the nitrite rises they just can't recover. I have seen fish with almost no fins due to ammonia burns as it can completely eat them away.

I would recommend daily water changes in your tank for a good week or two. Cut back on feedings no more than once per day and feed no more than they will eat completely in 3-4 minutes. Don't stir up the gravel during this time because you want to let your beneficial bacterial take hold and it lives mostly on surfaces in your tank, not so much the water itself.

Good luck and welcome to AA! You will find a wealth of information here and lots of people who want to help.