When I moved from a coastal village to the city, I decided to buy a larger aquarium. I spent a small fortune on aquatic plants and took my time setting it up. Finally the plants started to grow and I was very happy with the underwater garden. The fish I introduced did a good job at keeping down the algae and all was "peaceful". I visited a pet shop in the city and saw some fry in a large aquarium. For some reason I wanted to put some of them in my new set up. The owner said they'd probably be eaten by the other fish before the end of the day but sold me four larger ones that were born a few weeks before and were about 1cm long. When I arrived home and put these blue-eyed fish in the 304 litre aquarium, they immediately started exploring and seemed "happy". It was only when they started to grow and finally breed that I realised I'd made a mistake. Their constant digging uprooted all the plants and left my underwater garden a total wreck. The blue-eyed fish? T-bar cichlids - Cichlasoma sajica.
Now I have Anubias barteri floating around the tank rather than trying to keep plants attached to wood etc.