Glofish Tetra Aggression

[Madi1610]

Hi,
So I recently got a 10 gal tank for 6 glofish tetras and I had some issues at first. The first night I had one die and same for the second night and was confused so I tested my water and all the parameters are good and I haven’t had any issues. Then just recently I noticed one of my fish is missing it’s tail fin and the top fin is slightly mangled. I can’t quite tell if it’s a bully fish or not because tetras are playful nipping fish but I’m worried if it is a bully should I isolate it or no because they’re schooling fish. I’m kind of confused, any suggestions?

 

[SaraB]

10 gallons is too small for the glofish tetras. It sounds 100% like a bully fish.
Did you cycle the tank before adding the fish?
What are your water parameters exactly?

 

[Madi1610]

I didn’t. I cycled it with them in the tank. Risky I know, I am new to this and didn’t know better. Which I believe is why I had an ammonia spike that killed one of my fish. I don’t remember my parameters. I took a water sample in to get tested and everything came back normal