loss of appetite

For the past two days, one of my danios, a green glofish, has been lethargic and not eating very much. He is not swimming with the rest of the shoal and is just staying at the top of the tank and always moving his mouth. I was thinking it could maybe be ammonia posioning? The ammonia isn't very...

Hi. I'm new here, so bear with me. I have a 12 year old red devil that has suddenly taken a turn for the worst. His appetite has significantly decreased in the past week and he has been very lethargic, staying in one corner of the tank, nose up. I have struggled with hole in the head with him...