SO i was watching my fish today and noticed the smallest and first one i bought, a guppy, had his tail all tattered like he was being nipped. So i watched and noticed the 2 2nd smallest fish out of all my fish is being a bully.
I have 2 blackfin tetras
2 guppies 1 yellow and blue and 1 yellow and black -both male
2 swords- male and female
1 glolight tetra

Seems the yellow and black one is bullying the whole tank. I have had him since august and the whole place was a peaceful community.
Now it seems he is bullying the other guppy and both swords. I havent noticed any attacks on the glolight or blackfins.

I havent added any new fish, the only change has been the plants are starting to get good size. Why all of the sudden would this guppy start bullying?
Oh they get enough food. I feed 2 small meals a day. Actually try to give less than what i think instead of dosing the whole tank.


Edit: only new thing i actually added was a new heater. Temp is a steady 80. Would he be in mating mode?
Any advice

What size is the tank? It could be that there isn't enough room and he's just frustrated at being over crowded...

He could also just be a jerk. Each fish has it's own personality. I've known "peaceful community" fish that have turned out to be bullies. Fish are like people in that each one has it's own personality, and sometimes you just end up with a "jerk" fish.

IF your tank is big enough, I'd get more Black Fin Tetras and Glolight Tetras. They are both schooling fish and should be in schools of 6 or more. If you don't have the room, maybe re-home them or trade them in.

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