PARASITIC DISEASES

In discussing diseases with several of the guppy breeders with longest experience, their greatest difficulties have been shimmies and “ich’, both most often caused in Lebistesby parasites. Another has been troubled by velvet and another who feeds a great deal of live food which he collects from ponds, finds that hydra gives him no end of trouble. There is no uniformity of experience. Ichthyopthirius (Ich)
The microscopic protozoan parasite is named Ichthyophirius multifilis. It attaches itself to the guppy and gets inside the layers or under the skin. There it produces a white spot-sometimes a great many white spots can be seen on one fish. After a few days, depending on the temperature, it emerges and falls to the gravel bottom, and becomes a cyst inside of which hundreds or thousands of tiny parasites develop, eventually released to swim about in this infective stage. In this stage, they are able to live no more than ten days without nourishment and then only in cool water. So you almost never see “ich’ on guppies kept at 80 degrees or more in temperature.
Treatment: Raise the temperature to the 80 -85 degree range. Use any chemical treatment: (1) Metaphen. (2) Mercurochrome. (3) Methylene blue will destroy the organism but blues the tank’s contents. Owning my own guppies, I have never had “‘ich’ since a uniform temperature of 76 – 80 degrees was maintained. No treatment has been necessary.

Ichthyophonus

Ichthyophonus disease is caused by a small organism, Ichthyophonus hoferi, which attacks principally the ovary but is also found in other parts of the fish; causes the fish to become emaciated with a shrunken belly, lose its appetite and move with shaky and unnatural movements (not shimmy). On post mortem the ovary appears to contain a large number of yellowish-white knobs up to the size of a pinhead which are frequently mistaken for tubercles as seen in tuberculosis. The knobs fill the ovary as small ones grow on the larger. In time, the knobs grow through the skin; if the fish lives long enough, these can be seen plainly. Affected fishes have been known to live many months. No cure is known. The best method of control appears to be to remove all victims at the earliest signs of the disease.

Gyrodactylus

When guppies shimmy and when with careful observation you can discern a faint whitish abnormality on their scales, the chances are excellent that they have this tiny leech clinging to their scales and in their gills. This parasite has caused me more trouble than all other parasites combined and until I found cures for it, it made guppy keeping far less fun than it now is. An invasion of gyrodactylus causes a fish to shimmy his life away. It makes one shudder to realize what is happening, that is, when one knows the cause.
The parasite reproduces with great rapidity because of a curious fact. A young individual becomes sexually mature while still in its mother’s uterus and inside of it may be another sexually mature individual and so on. Four generations may be found, one inside the other. No wonder they multiply so rapidly.
The irritation they cause is by their hooks. Each has large (large considering their microscopic size) pair of hooks with which to anchor themselves, and, around their bases, sixteen marginal hooks. The body moves about standing upright from the base. It can elongate or withdraw in accordion-like movements. It is the presence of huge numbers which drives the guppy frantic and eventually kills him.
Treatment: For a slower, but effective cure, use formaldehyde. (2) For immediate curing use 3% ordinary (drugstore strength) hydrogen peroxide diluted with an equal amount of water. Catch all the fish in the tank in one net and dip them for two seconds in the solution. Return them at once to their home. Only very weak ones will succumb. Those without too many parasites will be only momentarily affected. It is seldom necessary to dip a single fish from that aquarium again. This is a drastic cure and is done at the fancier’s risk. Better try it on a few fish first to assure one’s self of the efficiency.

Velvet

A few of these parasites on a fish appear as “ich’. It is when the infestation is heavy and the numbers of organisms together give a velvety appearance that the seriousness of the condition becomes apparent. Velvet is caused by a small yellowish organism called Oodinium linineticum. It has whip-like flagellum to propel itself and another in a constriction in its middle.
On small fry velvet is particularly serious. The parasites have root-like tentacles which penetrate the fish’s skin and through which they draw nourishment from the body. During only the free-swimming, state it is infective. As soon as it anchors itself, it starts to become pear-shaped; the constriction about its middle disappears, and it grows to be about eight times the size of the free-swimming form. After few days feeding from the fish, it drops off and divides, as do its descendants, until it has become almost two-hundred of the free-swimming, infective forms.
Treatment: (1) Acriflavin. (2) Methylene blue diluted as much as one-hundredth of a grain in a gallon of water, killed velvet, provided the temperature has been maintained from 77 to 86 degrees. (3) Mercurochrome. (4) Salt water. Do not remove the fish until all the adult forms have dropped off. These are the hard forms to kill; the infective free-swimming form is easily destroyed. (5) Probably simplest-12 copper pennies in a gallon of water.

Leeches

In introducing pond water to tanks, one is quite likely to bring in a few leeches. These may be of many species. Some can be harmless plant leeches. Others live in the gravel, come out and move rapidly about in the water, especially if disturbed. To most persons this species is obnoxious, yet they do not touch the guppies. In rare instances a young leech may be found attached to a guppy’s side. They have been reported but I have never seen one.
Treatment: To eliminate all kinds of leeches from a tank, clean it completely. New water, new gravel, new plants. Leeches are both male and female in the same individual and need no partner to populate an aquarium when only one is left. In pouring out the old water, take care to see that no leechs slid down under the rim made by the top angle iron, or it will drop back again into the water later on. Any sucking leech clinging to a guppy must be pulled loose with tweezers. This is very dangerous to guppies

Fish Lice

This flat creature which lives on fish is a Copepod of which there are eight suborders, one of which is the argulus with twenty-two species found in America. The female louse lays from 30 to 200 eggs. The young must pass through eight transitions or stages before they become adult, a process requiring about eight weeks. Some are salt-water and some fresh-water forms. A. versicalor is prevalent in fresh water. It has two sucking discs, is about a sixteenth of an inch long. In outdoor pools it can destroy all the fish.
Treatment: (1) Salt water cure. (2) Potassium permanganate added to the tank at the rate of one-fourth grain per gallon once a week for three weeks. (3) Pick lice off u>ith tweezers and disinfect the spot.



ABNORMAL GROWTHS

Quite a wide variety of tumors appear on or in guppies. Some are benign, some malignant. Scientists are very interested in such growths but from a practical point of view, it is best to destroy affected fishes.



ENEMIES

Hydra

This little creature, anywhere from a third to one inch in length, is illustrative of how the guppy hobby carries us into related bypaths. Hydra are often introduced into aquaria with pond water and have become the “number one” enemies of guppies. To call them animals may seem like stretching a point if we judge from their appearance. A whole chapter could be written about them-here only the high spots. The animal attaches itself with a sticky substance to the glass or an object in the water. It cannot swim but it can move by a looping movement. The free end of the body has a conical projection called a hypostome on which its mouth is located. At its base is a circlet of long tentacles, five to ten in number. The hydra pulls the fry to its mouth by means of the tentacles, after interesting devices called menatocystshave caught it. Some of the menatocystscontain long spines in long rows. The prey is pierced and paralyzed by the spines whichinject poison. Other cells have thread tubes in them which can lash out and wind around any protuberances on the fry to hold it securely, aided by a glue-like substance which it secretes. In a daphniaculture hydra create havoc. Hydra, when at rest, contract into soft balls. After eating, too, they retract into irregular globular forms. Because they reproduce both by budding and by fertilized eggs, hydra breed very rapidly. They are difficult to eliminate from a tank by washing it or even drying because their eggs have a hard outer shell which resists both drying and washing. The contents of the shell come to life quickly once favorable conditions are established.
A heavy infestation of hydra can destroy or retard the growth of many fry both by killing them and by eating their food which starves them. Hydra are easily seen protruding from their attachments and swaying about.
Treatment: (1) Hydra cannot stand chlorine or heat. If you have city water, remove the fish, drain tank and fill with fresh water. Return guppies two or three days later to the tank. (2) Remove fish, raise water temperature to 105' for 24 hours. When the water has returned to normal, return the fish. (3) Use of ammonium nitrite or ammonium sulphate at the rate of 5 grains per gallon of water will destroy hydra. Dissolve crystals in small amount of water first, then pour this solution into the larger tank. In 3-5 days all hydra will be dead, the guppies remaining unharmed by the solution!!!


Almost all of the other guppy enemies are introduced unintentionally along with tubificids, daphnia or live plants. and belong to the insect kingdom. Nostof them are outdoor enemies, invading pools or large tanks in which fish are kept. There is no treatment for them that will not additionally effect your fish, so all you can do is put mosquito screening over the tanks to prevent entrance by the insects. Here are the principal insect enemies: Dragon fly larvae, Damsel fly larvae, Dobsonfly larvae, Water scorpions, Water boatmen, Back swimmers, Water tigers which are larvae of whirligig beetles, Water scavenger’s larvae, Predacious diving beetle larvae and the Giant water bug.


Leon F. Whitney, D.V.M..