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Guppy Diseases, Parasites, and Their Cures

Toxins in the Water: The Invisible Culprit.

Fish will often jump out of a toxic environment.

HEAVY METALS such as copper, iron, zinc, and lead destroy the fish's slime coat, cause blood patches, cloudy eyes, listlessness, and damage the gills, leading to death. Keep all metal out of the tank. If you have problems you cannot identify you may be able to link them to contamination from old copper pipes. While copper is sometimes used to cure protozoal diseases the concentration used is relatively safe. When treating fish with copper make sure your water conditioner does not deactivate heavy metals or it will have no effect.

OTHER TOXINS include chlorine, chloramines, chemical sprays used in the home, tobacco (via fumes or from fingernails put in the water), paint fumes, ammonia, unsuitable plastic decorations (don't use it if it smells strongly of plastic), or dead snails, which will quickly pollute an aquarium and kill the fish.

If you suspect toxins, carry out a 50% water change immediately and find the source of the trouble.


There are many diseases and parasites that can attack a Guppy. Here I will attempt to explain some of the most common ones guppies experience...

EXTERNAL PARASITES!

PROTOZOA (Single-celled animals)

Though only one cell, these can be large enough to be seen with the naked eye.

White Spot/Ichthyophthirius multifilis (short form, ich or ick) Often the first sign of infestation is that the Guppy rubs it's body against things in an effort to rid itself of the parasite. The entire body becomes covered in sand-like white spots. The parasite penetrates the skin and becomes a cyst, feeding on blood and skin cells. It grows for a few days it drops to the bottom of the tank and forms into a cyst and cell division creates up to 1000 zoospores, which try to attach to a fish within 70 hrs.- this is the infectious stage. This cycle takes about 5 days at 27C. The best time to attack ich is when the parasite leaves the fish, so raising the temperature helps to aim the medication at this stage. Salt is often used, but a store-bough remedy is a more certain cure, usually Malachite Green. This cure does stain some decorations. Other remedies are Clout and Aquarisol. It should be used for 15 or twenty days, depending on the temperature of the tank, so that 3 cycles of ich are completed. The fish should be quarantine for a month later so they cannot infect other fish.

Guppy Disease? There is actually a disease caused by a protozoan that is more commonly seen in Guppies than in other fish. This is a tiny parasite that attacks the skin and may even reach as far as the muscle or bloodstream. They may get large enough to resemble ich and the scales may protrude, swimming is difficult and the skin usually falls off as well. If this is not taken care of quickly it can spread throughout the tank and be very difficult to control. Some treatments that should work are Malachite Green, Copper (try Aquarisol), and Formalin (use this with caution). Clout is a good name-brand remedy which should take care it. This disease should not occur under clean, warm, Guppy conditions.

Velvet is similar to ich and it is highly infectious, however it is a curious dinoflagellate which contains chlorophyll as do plants, including algae. It looks like gold or brown dust, often appear to be grayish patches and bleeding can eventually occur, with the skin peeling off. When the gills are affected the fish will have difficulty breathing and may die from this alone.

The remedy often used for velvet is copper (try Aquarisol by Aquarium Products). The tank should also be darkened for the best results.

LARGER EXTERNAL PARASITES (multi-celled)

Anchor Worm : A crustacean (copepod), it is not really a worm. It resembles one as the female hangs out of the fish with a deep anchor. It can be up to 2 cm long and appears to be a Y-shaped twig with 2 egg sacs hanging from it. The fish can become weak and thin. The eggs are released and a hole is left in the fish which may become infected. This parasite usually affects only cold-water fish such as Goldfish but is sometimes seen in Guppies that have been raised in ponds or were recently imported. In my experience, it does not transmit very well in an aquarium, however an insecticide such as you would use to remove flukes from fish should be used.

Flukes!

These are smaller than anchor worms and basically invisible to the naked eye. There are several types of flukes (monogenetic) that show up in aquariums. These are all flatworms that grow only as long as 1 mm in length. Younger fish are particularly affected due to their size and action must be immediate. Luckily an organosphorous insecticide, trichloromethyl, takes care of all of them. However this ingredient breaks down quickly in warm, alkaline water, normally the Guppy's habitat, and a more aggressive treatment than what is prescribed on the remedies is needed. Flukes reappear and it may take many treatments before they are eradicated. Be careful not to contaminate other tanks when you see an outbreak because flukes can spread easily in just a drop of water! Make frequent water changes, keep the filter clean and rinse all maintenance gear with very hot water. A couple of brand-name remedies include Jungle's Parasite Guard and Aquarium Product's Life Bearer.

Gill Flukes "Gill Worms" : There are 3 types and their effect is sometimes called "Gill Disease". The symptoms are reddened/inflamed/bleeding/slimy gills, growths, and heavy breathing near the water surface. There are actually 3 types and they eventually destroy the gills. Diplozoa are large enough to be seen (1.5 cm) and appear to be a gray/brown worm in gills. The gills will bleed have trouble breathing.

Body Flukes: These seem to be common in Guppy tanks. Gyrodactylus, a sucking worm, is a live bearer on it's own. It attacks the skin and can only be seen under a microscope. The first symptom a Guppy shows is scratching itself on ornaments or the bottom in an effort to rid itself of the parasite. Imagine yourself with leeches all over! Fry normally display closed tails, or "pin tail" as they affect the fins. Heavy infestations cause a gray look to the skin, sometimes even with inflammation and redness. Usually fry are dead before they succumb to this symptom. Action must be immediate with young Guppies.

INTERNAL PARASITES!

Instestinal Worms: These are nematodes, also called roundworms or threadworms. The most commonly seen in Guppies is Camallanus, which can reach up to 2 cm in length. They are reddish-brown or orange, and can be seen protruding from the anus like a tiny paintbrush. These worms are occasionally seen in Guppies that have been kept in ponds and fed live Cyclops (avoid feeding your fish this food). Cyclops can also introduced through new live plants, so make sure to wash them throughly before adding them to your tank. Other intestinal worms usually do not pose a threat in aquariums since they have a rather complicated life cycle, but Camallanus nematodes are capable of passing from one fish to another. It may be advisable to destroy the infected fish unless it is a valuable breeder and use an anthelmintic treatment on the tank. Such medication is hard on guppies, particularly pregnant females. Garlic helps ward off these worms and many breeders add it their dry food or beef heart recipe.

FUNGUS

Fungus is actually a colourless plant and it gives a whitish cotton-wool look . Fungal diseases normally only attack weak Guppies where they have had damage to the skin or gills, or when the delicate slime layer has been weakened for some reason such a previous bacterial problem. Fungus also occurs when Guppies are kept in tanks that are too cold. Saprolegnia, however, seems to be a culprit in the death of fry, attacking the gills and causing massive deaths even before symptoms seem to show. Jungle's Small Fish Saver is made to combat this problem.

For a remedy, try raising the temperature of the tank. You should also remove the affected fish to a separate tank and use Malachite Green until the fungus is gone.

Columnaris is known as mouth fungus but is not really a fungal disease. It is caused by a bacterium. It rarely spreads from the mouth but it is very contagious and will destroy a whole tank of fish. At first it looks like a white line around the lips and then as cottony gray/white patches, and eventually can become open sores. The fish is unable to eat and toxins are created, causing rapid death.

Remove the fish A.S.A.P and treat with an antibiotic. If the fish's tank was overstocked it may to be an excellent idea to treat that tank with a wide-spectrum antibiotic to prevent further outbreaks.

FIN/TAIL ROT: This seems to generally be a bacterial problem in Guppies, however fin nips by aggressive tank mates or damage from sharp ornaments can cause physical damage to the tail and fungus sets in. It is important to distinguish which problem you are really dealing with before imposing medication. Fungus can also be a secondary problem that sets in after damage occurs from the bacterial disease which should be kept in mind.

A fish with an obvious bite out of his tail with a white edge has been infected by fungus and Malachite Green is the remedy of choice in a well-aerated hospital tank.

If there has been no obvious damage to the tail and the edge shows disintegration and shredding it should be assumed to be a bacterial infection and the fish should be separated and treated with an antibiotic such as Tetracycline, or Maracyn.

DROPSY: There are two forms this takes but both look similar, and both are caused by a bacterial infection. With one, the scales protrude from the body (like a pine cone) and with the other, the body swells with fluid which causes scale protrusion and protruding eyes.. This is actually the symptom and not the disease itself. Unfortunately, this is extremely difficult to cure. The fish should be isolated and destroyed if its condition does not get better. By the time the scales protrude, the internal organs including the liver has been damaged to the point of no return. The cause is what the fish keeper should study to avoid another case of dropsy. Poor water conditions, weakened fish and feeding too many bloodworms are often involved.

I suggest you read the page, "Hospital Tank" for basic information on administering treatments!