Philometrosis, Philometroidosis.
Contagious disease. A helminthic disease of many fish caused by several species of nematodes from the family Dracunculidae, belonging to the order Spirurida. In our waters, the nematode Philometroides lusiana is widespread. Mature helminths localize in muscle tissue, scale pockets, less often in the body cavity, while larval stages are found in internal organs (liver, kidneys, swim bladder, gonads). The development of the pathogen involves intermediate hosts — copepods (Cyclops). Mature females, upon reaching a water temperature of 16-18°C, begin releasing larvae and infest water bodies. Further development of the larvae occurs within the body of copepods.
The disease usually begins to manifest in May or June, depending on the water temperature regime. The extensiveness and intensity of the infestation increase from May to July. Heavily infected fry die. Fish infected during the summer period remain infested throughout the entire winter period until the spring of the next year. In warm water conditions and in the presence of intermediate hosts — Cyclops, the development time of the pathogen is reduced to 6 months, so infection can also occur in other seasons of the year.
Symptoms: •— The disease manifests as inflammation of the liver, swim bladder, and kidneys, accompanied by general intoxication. The disease proceeds acutely and chronically. An acute course is observed in 2-3 week-old fry during the spring-summer period. The initial stage of the disease is characterized by impaired coordination of movement. Fry rapidly and erratically move in the surface layer of water or sink head down and make circular motions. Such movements alternate with erratic movements on their side and jumping out of the water.
This course of the disease with sharply defined signs lasts for 1-3 days, after which the fry die. If the infected fish does not die soon, the disease takes a protracted, chronic course.
Emaciation, sluggish movements, and gill anemia are noted. The fish spends most of its time in the surface layer of water and feeds poorly. When helminths penetrate the scale pockets, bumps, swellings, and reddened areas appear on the body, scale protrusion is noted, and scales become dull. Parasites injure the skin and blood vessels. Bumps and bloody spots appear on the body.
The pigment of the scales is destroyed, a mosaic pattern appears on them, they stick out and fall off. In light-colored fish, red dots are visible through the scales. Helminths are most often localized under the scales around the head, in the dorsal part, on the sides and belly, and sometimes in the gill covers. The fungus Saprolegnia settles on the affected areas of the skin. The fish has a very unattractive appearance.
Treatment: Treatment has not been developed. Medications cannot be used because dead worms cannot be expelled outwards. Diseased fish at an early stage are destroyed, and the disease will subside since the larvae, having no intermediate host, will die. To avoid the penetration of dracunculid larvae into the aquarium and infection of the fish, fish should not be fed live zooplankton from water bodies populated by any ichthyofauna.
Camallanosis (camallanus worms).
Contagious disease. A helminthic disease of many fish caused by the nematode Camallanus cotti — another very dangerous representative of nematodes, increasingly found in aquariums. Small (1-2 cm) red-brown parasites belonging to the ascarid group. They live in the intestines of various fish. They are introduced with Daphnia and Cyclops. They are detected only when one or more worms protrude from the fish’s anus to release eggs with the fish’s feces.
Viviparous, developing on the bottom of the aquarium. For the development of the third infective stage, Camallanus cotti larvae do not need an intermediate host. In any case, this parasite does without an intermediate host for several generations and develops simply on the bottom of the aquarium. Many species of freshwater fish from the genera Poecilia, Xiphophorus, Symphysodon, Pterophyllum, Apistogramma, Macropodus, Corydoras, and others are susceptible to infestation. Viviparous fish are especially vulnerable to these parasites. Fish swallow larvae along with excrement or by eating the corpses of dead fish. Adult camallanids feed on blood, which they suck out of the intestinal wall, and are therefore colored blood-red. Fish infested with many worms can become emaciated and even die.
Symptoms. •— Due to blood loss, sick fish lose weight, their spine curves, growth is impaired, and intestinal inflammation and prolapse develop. The first sign of infection with these parasites is red-brown worms protruding from the fish’s anus. Often, the blood-red posterior end of the female helminth can be found hanging from the fish’s anus. Infected fish can live with these nematodes for a long time. However, constant blood loss greatly exhausts and weakens them, exposing them to the risk of contracting other diseases.
Treatment. Treatment is carried out in the general aquarium to destroy the parasites. These nematodes are very resistant to various drugs, so treatment is not always successful. Treatment with Masoten does not always lead to a positive result. Conkurat can be used by treating bloodworms with it and feeding them to sick fish. Fenbendazole, Levamisole, and Piperazine are also used. The medication is either administered internally with food (0.25%) or used in the form of prolonged baths in the aquarium, adding it directly to the tank every seven days for a total of three weeks.
After treatment, the fish should be kept in a quarantine aquarium for several days. Some time must pass for the dead helminths to detach from the intestinal wall and be expelled with feces. If female parasites are not seen emerging from the fish’s anus within a few days, the fish can be returned to the aquarium.
After successful treatment, fish recover quickly, provided good maintenance conditions are met. If infected fish accidentally get into the aquarium, good aquarium care (removal of excrement and dead fish) will help limit the spread of parasites. The aquarium that housed sick fish is completely emptied and disinfected to destroy nematode larvae.
Latest changes and additions made on August 13, 2012.
