Hello. Just registered this morning. I have a 30 gallon tank about 2 years old. I'm looking to do some modifications to the tank, ie., changing the environment. I currently have 3 Rosie Barbs (very healthy and hearty), a Spotted Cory Cat, and a small Algae Eater. I'm looking to switch the tank from a community tank to getting Cichlids. My Rosies are a bit aggressive and have owned the tank for the past 18 months. My Cory is one of the original fish. Might I encounter any problems if I were to change the structure (adding rocks/caves) and add a few Cichlids ??? Very curious. Many thanks for your replies.