hi i have a 200 litre tank with six red eye tetra a sailfin molly and last week i bought 2 keyhole cichlids and a german blue ram the other day i noticed one of my keyhole cichlids had one of his fins missing and also some of his tail fin this seemed to happen overnight and this morning when the lights came on my other keyhole has one of his fins missing even though he was fine last night any ideas what this could be?