1 tetra dead... another on his way

[JerryO]

2 weeks ago I noticed one of my neons was bloated and swimming on its side. I moved him to an isolation tank immediately for observation. Gave him some peas incase it was constipation and did daily 50% water changes dumbing the water from the isolation tank and replacing it with water from my main tank. The bloating went down but he remained on his side. As time went on his breathing was labored and swimming became erratic. Yesterday I lost him.

Today I find another neon having problems swimming upright. He is either head down or doing barrel rolls as he swims. He also seems to have problems with his buoyancy bobbing up and down between lower and mid tank. All similar behavior to the first tetra that was removed 2 weeks ago. I also noticed that this tetra has a large black tumor on his head (The other did not). It is possible that these are not related incidents but I am worried. I don’t want to lose these guys every few weeks until they are all gone. No one else is dispaying any strange behavior

HELP!!

Tank setup
10 months old
20 gal tall
1/3 water changes twice a week
1 male beta
13 neons (now 12)
diet for neons (flakes daily, cucumber 1 day week, peas 1 day week)
All parameters tested normal (testing every 3 days for last 2 weeks to make sure nothing is changing)

 

[Mr. Limpet]

Wish I could help you, but my Cardinal Tetras have been dying too and the best I can figure out is they're confirmed as wild caught and from researching them it seems that WC aren't as easy to acclimate to tanks as farm raised. Didn't notice any bloating and my tank is pristine.

We got 3 FR from another shop and they're doing fine.

Good luck and if you get any info, please post it.