I'm new to all of this, so bare with me. I recently acquired a 10 gal tank from my brother, that had already been set up. The tank included 2 small pelco's and 2 tetra's. I than went and got a blue gourami and a fire gourami. I have done a 50% water change just a couple days ago, it stays pretty clean. Anyways I have been noticing for the last couple of weeks that each species seems to attack each other for instance my Pelco's attack each other, the fire gourami attacks all of them and the tetra's fight each other. Just tonight I witnessed my fire gourami bite on to the blue's fin and attack him for about 30 seconds until I tapped on the tank. I don't know much about fish but I do know you keep communities together. My LFS told me that these were all community tropicals and they are not aggresive, but all I am witnessing is them trying to kill each other. Please help.