I have a 32gallon, fully planted and cycled for 2 years.
I have 7 neon tetra,4 glass catfish, 2 otos, 1 glass barb. Very peaceful and active group of fish.
Recently I added 4 black phantom tetra and that is where it all went down hill. It was two males and two females. The males would not stop fighting, but I assumed since they were tetra they needed a bigger school. So I got 2 more females, which didn't do much. So I had to take out one male and exchange him for a female. With a total of 5 females, and one male now they all fight.
Worst part is that my neon tetras are now aggressive as well, nipping and fighting among themselves
My water is always perfect, 30 percent changes every 2 weeks or less.
Only thing I can think of is that I recently (because of plants) I started using flourish and excel. I also started to use a different kind of water conditioner at the same time, the bigals stuff (my old topfin stuff ran out). All these were at the exact time I put in the phantom...
But could it be mating season for tetra? they are only being aggressive with their own breed. Is this a stupid thought? all my pther fish are peacefu ad keep to themselves.
Any help would be amazing....