While in many cases it is 1 or 6+, this isn't necessarily a rule. I had 2 together in my 150 for a while. One about 7", one about 4". The were originally divided, but then actually together for several months. Surprisingly, the little one was the bully. It wasn't anything really bad, just some chasing. My larger flagtail was actually very peaceful with my other one.
They are currently separated again, but when I get a larger tank, I would like to try them together again, possibly with another one or two (or more if the tank is big enough)
They are currently separated again, but when I get a larger tank, I would like to try them together again, possibly with another one or two (or more if the tank is big enough)
