Sickness and Treatment: Hexamita and Spironucleus vortens

Hexamita is a flagellated protozoan disease which is often confused with Spironucleus. Spironucleus is responsible for what is commonly called hole in the head disease.

Hexamita is a well known problem in cichlids which seem to be quite susceptible to it but it isn't just a cichlid problem, almost any fish can suffer from hexamita.

Hexamita is normally found benignly living in the fishes gut. If the fish are placed under stress their immune system can be compromised and opportunistic infections will occur because the hexamita is allowed to increase in numbers relatively unchecked and it is able to leave the gut and get in to the blood stream of the fish.

Each flagellated protozoa can reproduce just 24hrs after being born so once established in a host the disease is able to spread very quickly.

• Hexamita is normally found in small numbers in the gut of fishes. When a fish is stressed due to overcrowding, shipping, poor water quality, bullying, wrong water chemistry and so on its immune system works less efficiently. This allows the hexamita to increase in numbers and move up from the gut in to the lumen of the upper intestine where it is able to swim freely in the intestinal fluids and eventually in to the bloodstream of the fish where it then spreads to the internal organs.

• White stringy faeces is classic symptom of hexamita.
• Infected fish lose their appetite and lose condition as a result, this makes the fish lethargic.
• If the internal organs are affected, particularly the liver and kidneys the fish may lose control of its osmoregulation and show signs of dropsy.
• Secondary bacterial infections of the skin are common in infected fish.
• Occasionally swimming abnormalities can occur if the brain of the fish becomes infected.
• Once established in an aquarium Hexamita can reach such high numbers that new healthy fish added to the system will quickly be overwhelmed and succumb to the disease.
• The fins of infected fish may lose the tissue between the rays of the fins making them look ragged.

• Metronidazole at 50mg/l in a bath for up to ten days is usually effective.
• Once the Hexamita has been treated the secondary infections will need treatment accordingly. (Eg. Tetracycline for hole in head scars)
• If the fish has suffered from dropsy to much damage may have occurred to the fish's organs due to the dropsy and its survival is less likely

(Spironucleus vortens)

• This disease normally only affects cichlids. It is caused by a protozoa called Spironucleus vortens which normally lives harmlessly in a fishes gut.
• If the fish becomes stressed the immune system can be compromised and the Spironucleus vortens protozoa is then able to increase in numbers and spread through the fish's blood stream.

• When the parasite is in high numbers due to the immune system being compromised it is able to spread from the gut and get in to the blood of the fish where it can infect other areas of the fish. The protozoa damages the fish's gut wall in doing this and in turn it affects the fish's ability to digest food. Affected fish often lose condition and pass jelly like faeces.
• The characteristic symptom of the disease is small holes in the the head and lateral line of a fish which usually start at the sensory pores of the fish. It is thought that the parasite blocks the blood vessels to these areas causing tissue death and ulcers. Spironucleus vortens can also be found at these sites.
• This disease is often confused with hexamita which is a different but very similar disease but with different symptoms.

All cichlids are at risk of catching this disease and discus seem to be most at risk closely followed by oscars. There are several symptoms but an infected fish may not show all of the possible symptoms.

• Darkened colours.
• Poor appetite.
• Enlarged sensory pores on the head and lateral line.
• White discharge from the pores
• Ulceration of the head and lateral line.

• Metronidazole is the best treatment. The recommended dose is :A quarter of a teaspoon per 75 litres. (I always recommend if you buy metro try follow the directions as dosage strength may differ)
• Treat every 24 hours with a 25% water change made before each treatment.

On completion of treatment:

• Don't expect to see the ulcers all healed up. The ulcers are just a symptom of the disease and they will take time to heal once the Spironucleus vortens protozoa has been killed off. Healing should start within a few days of the treatment.
• This disease mostly affects fish which are stressed due to over crowding, poor conditions including poor water chemistry or poor water quality. If these causing factors are not dealt with then the fish won't respond to the medication quite as well as they might and there is every chance that the disease will return.
• With deep open wounds secondary infections pose a greater risk then normal. If the wounds become infected it will prevent healing so until healing has begun keep a very close eye on the wounds.
• There is no need to treat the fish if no infection is present.
• I have seen cases where at this stage you can use betadine on the holes or add tetracycline but depends on the severity