Reply To: IDing rainbowfish (species and gender) Welcome to the website! › Forums › Other Freshwater Fishes › Species Discussion › IDing rainbowfish (species and gender) › Reply To: IDing rainbowfish (species and gender) October 26, 2007 at 10:26 pm #12781 CrazedpufferParticipant I will guarantee that they will. The most aggresive fish in my tank with rainbows got along with CPDS so I cant see rainbows being aggressive.