What is wrong with my fish? Please help.

[morganlikesfish]

I noticed a few days ago that one of my tetras was swimming erratically, like in the video. It had now been a couple of days and this behavior has increased. When he’s not flitting about like this, he seems lethargic/ half dead. The rest of my fish are okay, I did have a higher ammonia level recently that is in the process of going down. Can anyone tell me what I should do?

 

[seangee]

The only time I have seen that in tetras it was a protozoan infection in the brain. In the UK we can't get antibiotics without a prescription and going to a vet is horrendously expensive. I did try everything that is available over the counter.
From my experience the fish will die (sorry) and if he does so in the tank there is a good chance it will be passed on to another fish. It literally swept through my tank one fish at a time.

I would euthanase and keep a close eye on the rest.

 

[Colin_T]

It either has a brain injury or an infection in the brain. There's no cure so euthanise the fish. Then do a 75% water change and gravel clean the substrate every day for a week. Clean the filter too if it hasn't been done in the last 2 weeks.

Cleaning the tank, filter and gravel will reduce the number of disease organisms in the water and hopefully prevent more fish catching it (assuming it's a disease).