Tetra Medica HexaEx is a highly effective remedy for endoparasitic flagellates (Hexamita, Spironucleus, etc.), which are commonly found in the intestines of American cichlids. Disease symptoms: These tend to be rather generic at first. For example, the fish may become withdrawn or there my be change in fish colour (particularly a darkening of the skin in discus fish). Other signs include fish that lose weight and have slimy, gel-like faeces containing intestinal flagellates that can be viewed under a microscope. In the advanced stages of the disease, holes and crater-like cavities may start to develop on the skin of the fish, particularly around the head (-hole in the head- disease).