I just recently purchased 6 cardinal tetras yesterday for my cycled 10 gallon. The problem is the 6 cardinals are hiding in the back of the tank and remain inactive. They don't swim but just stay huddled together. The tank is heavily planted with java fern and java moss and has driftwood with plenty of hiding spots and the only other occupants are 2 bronze cory. Water parameters are fine with no ammonia or nitrate, I even added blackwater extract to match the cardinal's natural environment. Any suggestions on how to get them to be more active or solve their shyness problem would be appreciated Thanks.