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DISEASES OF NOTHOS

There are several health issues that affect Nothos and the important to recognize and properly treat them. Beginners, in particular, need to be aware of some of the important diseases which exist within the hobby and even advanced breeders sometimes miss the same problems.

The Notho Disease *Glugea* – Glugea is probably the single most devastating disease currently known to killifish hobbyists. While it is not as common as it was in the 1990s and early 2000s, it is a disease all breeders and collectors should know and recognize. Glugea is a microsporidium protozoan parasite which infects the internal organs and slowly kills the fish. This is a rapidly spreading infectious disease most likely spread by the ingestion of spores.

Symptoms – The first indication a tank may be infected is a massive die-off of young fish shortly after they reach maturity. The fish may develop distended abdomens. In those cases, histological examination most often reveals white nodules throughout the abdomen. On rare cases, sores and nodules may appear on the body of the fish.

One reason this disease is so difficult to deal with is Glugea reproduces by creating spores that survive long-term drying in peat, are nearly impossible to eradicate without serious choline cleaning of the aquarium and will never be eliminated from any other items contained within the aquarium (filfers, gravel etc.). Nothos feeding from foods on the bottom can ingest these spores and the infection takes hold. This means that even if the breeder eliminates the infected parents and stores the eggs, the spores will remain in the peat moss and re-infect the next generation of fish.

Treatment – To eliminate this infection is not easy, but there has been some recorded success with the use of flubendazole and related products in infected fish. Unfortunately this drug is not easily obtained and finding a source may be difficult.

It is absolutely necessary to sterilize any tanks, filters and equipment which may have come into contact with the disease. Tanks should be thoroughly cleaned with strong, chlorine-based bleach. It would be wise to completely remove and destroy any replaceable equipment such as filters, tubing and ornaments (while it may seem extreme, if these items are infected with the spores and thrown in the garbage, there is a slender possibility the spore could be introduced through runoff to local water sources).

Although some breeders in the 1990s experimented by removing the eggs of infected fish from the spawning media and washing the eggs, this could not guarantee the infestation was removed. The wisest course of action would be to destroy the eggs and spawning media and obtain new stock from a trusted source. However, current discussion indicates early treatment of the fry (prior to or at maturation) with flubendazole may eliminate the sporazoan infection before it takes hold. This is only a suggested consideration and should not be taken as a definitive treatment

  • Velvet (Oodinium): The scourge of Nothobranchius fry, this external dinoflagellate parasite is probably the cause of more deaths of very young fish than any other.

SymptomsVelvet is easily detectable on adult fish, creating a coppery or golden dust appearance on the fins and body. Unfortunately, it is nearly impossible to detect with the naked eye on fry and requires a magnifying glass to ascertain the infection. Very often, the fry are infected with the parasite and even once identified, most of the time it is too late to effect a cure.

A tank can become infected in a couple of ways. Introduction of new fish which have been exposed to Velvet is common, but the more likely culprit in Nothos and other annuals deals with the overall life cycle of the organism. Once introduced into a tank, however that may happen, a single Oodinium dinospore will find a host fish and attach to it. After a period of 3-7 days, the mature parasite will drop off and swell up, becoming cyst and creating more than 200 new spores. In this stage, the cysts can survive for a long time if maintained in spawning media stored for egg incubation. Once fully developed, the spores are released and move throughout the environment. Oodinium dinospores have two flagella (tails) which provide the locomotion. The dinospores can live for several days without a host.

Treatment – The best treatment by far is prevention. Prevention of Velvet infestations is quite easy. The addition of at least one teaspoon of salt (preferably marine salts, but kosher salts are acceptable) will protect the fry from the development of Oodinium.

Commercial preparations – many copper based with a dye – do work once the disease is identified. It can take up to a week before the treatment effects a cure. Raising the temperature of the infected aquarium to over 85F speeds up the life cycle and will shorten the treatment period.

      • Mycobacteriosis – Mycobacteriosis was formerly known as “Fish Tuberculosis” or “Fish TB”. Although not common, Mycobacteriosis occasionally rears its head in the home aquaria. There are several forms of this infection, but two are the most common – M. marinum and M. fortuitum

Symptoms – The affected fish will become listless; hollow-bellied and refuse food in later stages. Other symptoms may include finrot, pop-eye and blotting. This disease is a little different in that the organism is defined as a fungal bacterium.

For the hobbyist, this means it generally cannot be treated by most antibiotics because the outer membrane of the organism blocks absorption. For the same reason, it is very difficult to remove from the home aquaria with most agents. In addition, it is possible for this disease to be passed on to humans, generally through open cuts that come into direct contact with infected fish or water. The only treatment for the hobbyist is a long-term antibiotic regimen.

Treatment – There is little that can be done to treat fish exhibiting this disease and they should be euthanized. There are a few reports that sulfafurazole, doxyclycline and minocycline may be used to treat this disease, but it must be applied by injection.

What is of more importance is treatment of the aquarium that contained the affected fish. This tank and all associated equipment will need to be disinfected (or destroyed) to remove the mycobacterium. There are reports strong chlorine bleach for an extended period followed by drying should remove the infection, however, weak bleaching mixtures definitely do not work. The addition of a strong alcohol solution (over 70%) to the affected aquarium after complete drying of the bleach will enhance the likelihood of eliminating the organism. Formaldehyde and some related disinfectants are effective in killing the TB.

  • Dropsy – A condition also known as ‘bloating’ usually affects a single fish or a small number in an aquarium and is considered a problem with the health of the tank.

Symptoms – The most obvious indication of Dropsy is a fish that appears bloated (hence the name) with its scales standing on edge. Current thinking tends to see this condition being caused by retention of fluids. The direct cause is unknown, but the indirect cause is kidney failure. Generally, it is older fish which seem prone to the condition.

Treatment – It is extremely uncommon for a fish to recover from this condition. Certainly a complete water change in the aquarium and providing healthy and comfortable quarters for the fish will help and some fish will live for a longer time. What is of more importance is the sterilization of an affected tank following the elimination of the fish. Again, chlorine bleach and drying is the recommended process before putting the aquarium back in use.

Nothos can be affected by many of the other common aquarium diseases such as Ich and Body Fungus.  These simply follow the normal cure processes used for the general aquarium hobby.
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