My mion fish mainly swims at the top of the tank. Looks like he`s gasping for breath were as the other fish are totally fine, he usually swam around the bottom, and swam against the spray on the outlet of the filter.. Im just concernd incase he is ill.. and if he is how can i solve it, all the readings are fine.. the others eat were he will not, tried different foods, which the others devower, were with him he just lest the food glide past him, he usally ate quite a bit... any help on this pls...