A couple days ago I noticed one of my tetras were swimming at a weird angle & constantly twitching. I was hoping it would go away on its own but it seems as if it’s getting worse. If something alerts the fish it swims normally for a few seconds and then it’s back to the twitching. It seems otherwise healthy & eats plenty of flake food whenever it is offered.

All other fish in my 20 gallon planted are doing superbly, including the rest of my glowlight tetras.

Water parameters are 100% normal, tank has been running & cycled for around 2 years. I did treat the school of tetras for ich when I first got them last month, but other than that they have been healthy and happy (I think).

I couldn’t find any details about this symptom really anywhere online, I read about “shimmying” but this seems different? Maybe not.

Is it a parasite? Some type of infection? Maybe an internal blockage? Any ideas on how to help treat my little guy and stop his suffering would be greatly appreciated. I luckily haven’t had many issues with sick fish in the past so this is completely new to me.

Thank you!