Parasitic Diseases
A large number of species of parasitic invertebrates plague both marine and freshwater aquarium animals. Some are quite specific in their hosts, affecting only one species, for example, while others are opportunistic and attack a wide variety of animals. Entire volumes are devoted to these successful but troublesome creatures, so only the more commonly encountered types will be discussed below.
In common with many parasitic diseases, coral reef disease is fatal if left unchecked. The parasite that causes the disease, a protozoan known as
A variety of copper-based medications are effective in the treatment of coral reef disease. As with all medications containing copper, it is important that invertebrates are not housed in the tank to be treated, or they will be killed. Note also that copper is toxic to many fish species at high levels, so be sure to follow the manufacturer's directions carefully.
The medication must be continued for at least two weeks after the parasitic cysts have disappeared, because the parasite is quite resilient during this stage and will only succumb to treatment when in its free swimming form.
Fish parasites are usually resistant to medication during the cyst and egg stages of their life cycles, and must be killed during their free swimming stage. It is, therefore, important to know how long the cyst or egg stage lasts and to follow the manufacturer's recommendation concerning treatment duration.
Also known as white spot disease, ick is transmitted by protozoans of the genus Crytocarya. These organisms are widespread in both freshwater and marine environments and are often present in aquariums. They generally affect only animals whose immune systems have been compromised by exposure to rapidly fluctuating temperatures. Once the disease takes hold, however, it is readily transmitted to healthy individuals. White spot disease most commonly occurs soon after fish are introduced into a new aquarium, such as when they arrive at a pet store or pet owner's home. It is during these times that the animal has most likely experienced stresses due to changes in environment or temperature fluctuations while in transit.
Ick is diagnosed by the presence of large white spots on the fish's body. A number of readily available medications effectively treat this condition. The protozoan species that causes the disease has a life cycle that averages twenty-one days in length. Because the parasite is resistant to treatment during the cyst stage, medication should be continued for at least twenty-one days. The contagious nature of this disease usually dictates that all animals living with the affected individual be treated.
A variety of conditions caused by several parasites are commonly termed “gas bubble disease.” Although the process of infection is not completely understood, it seems that air bubbles attach to the bodies of affected fish and create conditions favorable to bacterial growth. Water that is supersaturated with oxygen or nitrogen has been implicated in certain, but by no means all, cases.
In its early stages, gas bubble disease can be treated by pricking the affected area with a sterilized needle and releasing the enclosed air bubble through massage (the fish should be carefully held underwater during this process). A wide spectrum antibacterial should then be swabbed on the wound site. Advanced cases are nearly always fatal.
A related ailment specific to male seahorses is the buildup of gases within the brood pouch. Affected animals float to the surface of the aquarium in a head down position. This condition, the cause of which is as yet unknown, may sometimes be cured by gently massaging the inside of the pouch with a tiny, sterile pipette. After the gas has been expelled, the pouch should be flushed with a broad-spectrum antifungal medication.
Although marine clown fish are particularly susceptible to the protozoan that causes this disease (
Disease organisms affect different species of fish in varying ways. While some may respond to treatment long after symptoms have appeared, others may expire within a day of encountering certain parasites. As with most aquarium problems, vigilant observation and sound husbandry is your best defense.
A variety of medications, usually containing some form of malachite green, can be used to treat clown fish disease. However, action must be taken quickly. Unfortunately, by the time symptoms appear, the disease is often well advanced and not responsive to treatment. It is, therefore, extremely important to carefully monitor your pets so as to detect changes in their condition as soon as they occur.
Flukes are fairly large trematode worms that are usually readily visible to the naked eye. They are quite mobile and may move about the aquarium from fish to fish. Flukes are external parasites that use their hooked mouth parts to attach themselves to the skin or scales of their hosts. The resulting lesions may, as with any injury, give rise to secondary bacterial infections that further complicate treatment. In addition to direct observation of the flukes, infestations may be diagnosed by increased rates of respiration, and in some fish species, by a paling of the skin coloration. Affected fish also will be seen to frequently rub themselves against rocks and the substrate in an effort to dislodge the parasites.
Formalin based medications are most commonly used to treat fluke infestations. Other medications may be required to assist with wound healing and to kill opportunistic bacteria.
While some copepod species are important food items for small fish, others are dangerous parasites that attack a wide variety of marine and freshwater species. They are external parasites, attaching to numerous locations on the body, and most are visible to the naked eye.
A number of copper based products will effectively eliminate copepods from the aquarium. The eggs are, however, unaffected by most medications, and so treatment must continue for the parasite's entire lifecycle. Depending on the species, eggs may take up to five weeks to hatch. It is, there-fore, important to follow the manufacturer's directions as to the length of the medication period.
