Caring for your fish

HEXAMITA is a flagellated protozoa (Protozoon) that lives in the intestinal tract of fish. They are ever present in the intestinal tract of fish and are like a certain strain of E. coli bacteria found in our own intestinal tract that helps with our digestion. 
Hexamita coexists with the fish and may benefit the fish's digestion system. However, Hexamita can be good and bad at the same time.  Hex may be beneficial for digestion and nutrient absorption but an over population of hex will overwhelm the fish's intestinal tract. 
The fish's immune system may be the key to controling the hex population. Hex mostly occurs due to poor water quality, a sudden change in water temperature and the long haul shipment the fish goes through.  All these are stress inducing situations that would cause the fish's immune system to weaken. Once the immune system is weakened, it cannot keep the hex population in check. And like all simple cellular organisms, the Hexamita multiply very quickly. 
The over-population of Hexamita protozoa will cause irritation of the intestinal tract. Within days, the raw intestinal tract will be shed and excreted by the fish. Being in this condition with an upset stomach, the fish may try to eat but the food will cause more pain to the intestinal tract. This pain may cause the fish to totally avoid all forms of food.
Hexamita is probably transmitted through the water from contaminated fecal material. The flagellated stage makes its way to the lumen of the upper intestine. There, it swims freely in the intestinal and fecal fluids. The organism may be present in small numbers under normal circumstances; however, for the disease to develop, the organism must reproduce rapidly, resulting in a massive infestation. Generation time for the flagellated form is thought to be 24 hours.
Many ornamental fish also have susceptibility to this disease. Differential diagnostic procedures are required to identify the same problem. If you have kept South American cichlids, you may be familiar with the susceptibility of this disease in Oscar (Astronotus ocellatus). It is often referred to as a hole in the head which is caused by the Hexamita parasite. However, in flowerhorn it may not always manifest itself visually as it does with the hole in the head.  Angel fish which are severely infected with Hexamita may lie horizontally on the surface of the water with their abdomen visibly distended. Angel fish may remain in this condition for several days. 
So for controlling this disease, the first step is to combat stress, particularly stress caused by poor water quality or inadequate nutrition. These two kinds of stress seem to be associated with increases in the number of flagellates in the gut and development of clinical disease. Elimination of stress and correction of husbandry will help correct an outbreak of Hexamitiasis. 
Metronidazole provided as a medicated feed or a bath is also an effective treatment and even severely affected fish often respond to therapy, but the exact procedure of treatment is a must. Commercial producers of ornamental cichlids should periodically check the fish for Hexamita infections and treat any infected fish.