I have 6 rummy nose tetras which have been in my tank for around 2 weeks. I think the smallest tetra was getting bullied as he spent a lot if time hiding in the corner and behind a plant. He started coming out from the plant and swimming with the others and seemed fine for a few days. I have since added 6 male guppies and they seem to be mixing and swimming around together apart from the small guppy who has started hiding again. He comes out from time to time for a swim but not very often. His face is not red and the same colour as his body. He has been eating well but hasn't seemed interested today. Please help as I am worried he isn't going to make it.