one day my dad decides to drop a marble he found into the community tank. within days we could hear something tapping against the glass harder than the usual bump by the floating thermometer. we didn't know what to make of the whole thing until the obvious give away right underneath our noses was pointed out by my mom, the marble was in different locations at different hours of the day. our suspicions grew and with a close eye on the situation it was confirmed. the chinese algae eater LOVED that marble. he sucked on it and sucked on it and then all of a sudden push it with his head a good ways. we were speechless. he grew to love that marble as the weeks went by. soon all he did all day was chase that marble around here and there and frequently smack it HARD against the glass. by far that has to be the wackiest fish i have ever possessed. he lived a long and happy life.